President Barack Obama begins his re-election campaign defending traditionally Republican territory that he carried when he won the White House four years ago. Republican Mitt Romney is looking to reclaim any combination of these GOP strongholds now in flux.

In the months leading to the Nov. 6 election, both men will talk about how they will galvanize the nation. But in reality, they will lavish travel, advertising and staff on only a dozen states, and even fewer as the vote nears.

The political spotlight will shine brightly again on Florida, and the Upper Midwest, especially Ohio. But changes in the nation's demographics will mean heavy attention paid to the Mid-Atlantic and Southwest.

"For a long time the map was static. I don't think that holds true anymore," said Tad Devine, a senior adviser to former Democratic presidential nominees Al Gore and John Kerry. "Places like North Carolina and Virginia are changing, and they are getting a fresh look."

Despite the candidates' effort to make the election a national referendum, local trends and factors may decide whether campaigns go all-out in a state or bail to channel resources elsewhere.

It's a chess game aimed at reaching the 270 electoral votes needed to win.

Obama's flips

If the election were held now, Obama would safely carry 14 states, mainly the East and West Coasts, and the District of Columbia, with a total of 186 electoral votes. Romney, a former Massachusetts governor, probably would prevail in 20 states, primarily in the South and West, worth 156.

Both campaigns agree the election will turn on the 16 remaining states, and probably in those won by Obama in 2008 against Sen. John McCain, R-Ariz.

Obama expanded the Democratic footprint on an electoral map that had changed little between George W. Bush's narrow 2000 election and 2004 re-election. Against McCain, Obama captured nine states that Bush had won four years earlier.

Besides Florida and Ohio, Obama took North Carolina and Virginia, where a Democrat had not won in a generation. There were victories as well in Colorado, Indiana, Iowa, New Mexico and Nevada.

In Florida, unemployment tops 9 percent, tourism is slow to recover, gas prices are high and trouble persists in the housing market; all that works against Obama.

But his team is aggressively organizing in the state, and his visit Friday was his 16th since taking office, more than almost any other swing state.

Romney's battle with Rick Santorum for the GOP nomination slowed his preparations for the fall showdown in Florida. If Romney were to win the state's 29 electoral votes, it would block Obama's clearest path to 270, said Rick Wiley, political director for the Republican National Committee.

"Deny him Florida and his map alters significantly," Wiley said.

Ohio, too, is a jump-ball. In 2010, Republicans roared back. The manufacturing economy, especially its automotive parts sector in northern Ohio, continues to struggle, although unemployment has dropped below the national average.

"In Ohio, you're looking at the general election as a referendum on the economy," senior Romney adviser Kevin Madden said.

Yet Romney must contend in Ohio with the fallout from a party feud and an Obama campaign that never quit organizing after winning the state in 2008.

Republicans see North Carolina and Virginia as Romney's best chance to pick up an Obama-carried state.

Unemployment has remained at nearly 10 percent. Virginia Republicans have been emboldened by Gov. Bob McDonald, who in 2010 ended consecutive Democratic administrations. But the states' conservative complexion has changed.

Younger, Democratic-leaning professionals have flocked to North Carolina's Research Triangle and the northern Virginia suburbs around the nation's capital. Both states also have large minority populations; those groups voted in record numbers for Obama in 2008.

Obama picked Charlotte, N.C., for the Democratic National Convention in September. While convention hosts have been unreliable general election indicators, Obama was the first Democrat to carry Colorado since 1992 after accepting the nomination in Denver. Obama kept thousands of the volunteers he sent out for that convention to work through the election, as he could in North Carolina.

Though defending inroads into Republican states, Obama has an advantage of forcing Romney to spend money there, and that, Obama aides say, shows some of the options of reaching 270.

"We have an ability to win in a number of different scenarios," said Obama's campaign manager, Jim Messina. "The map has moved. This is not your parents' electoral map."

Hispanic voters helped Obama win last time in Colorado, Nevada and New Mexico, and, according to polls, they prefer him over Romney. Romney described GOP primary rivals Rick Perry and Newt Gingrich as soft on illegal immigration, and has said he would veto legislation that would allow certain illegal residents to become U.S. citizens.

But Romney expects to be competitive in all three states. For one, Nevada has a popular Republican governor, Brian Sandoval, who endorsed Romney on Wednesday. Also, unemployment tops 12 percent in Nevada, the heart of the housing crisis.

The Obama campaign is confident it will carry Colorado, where suburban women, a strong suit nationally for the president, in the Denver area are seen as key.

New Mexico has gone back and forth for the past three presidential cycles, and elected a Republican governor in 2010. But the boom in the Hispanic voting population is a challenge for Romney.

"Those Western states are going to depend on the Hispanic turnout and the percentage we get," said Charlie Black, a veteran Republican presidential consultant. "And if we voted today, we wouldn't do well. But we've got plenty of time to work on it."

Iowa, a true swing state over the past three presidential elections, is special to Obama. His upset of Hillary Rodham Clinton in the 2008 caucuses set him on the path to the nomination, and he has kept the fires burning.

Romney waged competitive campaigns for the 2008 and 2012 caucuses, but has struggled to win devotion from conservatives. On Tuesday, he received the endorsement of Gov. Terry Branstad, an economic conservative and establishment GOP figure.

Vice President Joe Biden has campaigned in Iowa twice this year. The Obama campaign included Iowa, along with Colorado, Florida, Nevada, Ohio and Virginia, last week a round of television advertising, highlighting its place as a top target.

Of the GOP states Obama picked off, only Indiana is viewed as uncompetitive in 2012. Obama was the first Democrat to carry Indiana since 1964, and he did so by a single percentage point.

But Obama did win New Hampshire, which flipped from Bush to Kerry in 2004, and is considered a toss-up this year. It's Romney's backyard, where he won the January GOP primary and Republicans have roared back to power in recent years. Biden campaigning in the state Thursday.

Democratic leaners

Minnesota, Wisconsin, Michigan and Pennsylvania are viewed as competitive, but lean toward Obama's column. Democratic presidential candidates have carried them since at least the 1980s, and earlier.

Romney hopes his native Michigan status and family name — his father was governor in the 1960s — help, as does his business background, given that the state's jobless rate exceeds the national average. But his opposition to the federal auto industry bailout in 2008 may hurt him in the car capital.

Although Romney's national campaign headquarters is in Boston, Republicans say they don't expect Romney to win, and perhaps not compete, in Massachusetts, a traditional Democratic stronghold.

In Wisconsin, conservatives are rallying around Gov. Scott Walker, who faces a June recall election after he signed legislation last year stripping public employee unions of most bargaining power. If Walker prevails, it could embolden Romney.

Bush competed in Minnesota and Pennsylvania in 2000 and 2004, only to have them tip Democrat in the closing weeks. Today, registered Democrats in Pennsylvania outnumber Republicans by nearly 1 million. But a downturn in the economy, or Romney catching fire elsewhere in the nation's economic heartland could tip both Republican.

Republican leaners

Obama campaign aides have sent signals they will contest Arizona, arguing the Hispanic voter trend favors them. However, they and Romney aides say that tipping point is years away and that it remains a safe Republican state.

Likewise, Missouri has been decided by slim margins in the past three elections, but carried by Republicans in all three.

As in Arizona and even Georgia, where Obama's team has also made overtures, Missouri is considered GOP territory this year.

"The Romney campaign is going to make sure we have the resources to compete in states where Democrats throw a head fake," Romney's Madden said. "And I'm saying Missouri is not being targeted by the Democrats."

An analysis of the state-by-state race to 270 electoral votes, the total needed to win the presidency, and where Democratic incumbent Barack Obama and likely Republican nominee Mitt Romney stand now. The numbers reflect electoral votes:

SOLIDLY DEMOCRATIC (186):

California, Connecticut, Delaware, District of Columbia, Hawaii, Illinois, Maine, Maryland, Massachusetts, New York, New Jersey, Oregon, Rhode Island, Vermont and Washington.

LEANING DEMOCRAT (56):

Michigan (16) — Despite lingering economic pain in auto capital, Michigan has large minority and union voting blocs that favor Obama. Romney, a native son whose dad was governor, won the GOP primary but his opposition to 2008 auto bailout will hurt him.

Minnesota (10) — Low unemployment and a long streak of Democrats carrying Minnesota give Obama confidence. But Minnesota was competitive in 2000 and 2004, and includes a length of the Mississippi River Valley, among the Midwest's most pivotal swing regions.

Pennsylvania (20) — Typically an early battleground, Pennsylvania has tipped Democrat in the final month in recent presidential races. Romney continued campaigning ahead of the April 24 primary before effectively sealing the nomination Tuesday. But a nearly 1 million Democratic edge in voter registration makes the state a reach for the GOP.

Wisconsin (10) — Ronald Reagan was last Republican to carry Wisconsin; Democrats eked by in 2000 and 2004. The June recall of GOP Gov. Scott Walker over anti-union legislation will test labor's strength. If Walker is retained, Romney could be competitive.

UP FOR GRABS (105):

Colorado (9) — Long a reliable GOP state, but Colorado's conservative profile is changing. An influx of young professionals and Hispanic voters were keys to Obama's victory in 2008. The economy has hurt him standing. Female voters in vote-rich Denver suburbs are likely to be key.

Florida (29) — Florida is the prime target for both campaigns. Obama won in 2008, but the housing crisis, high unemployment and gas prices are dogging him. Romney won the primary in January and has picked up endorsement of freshman Sen. Marco Rubio. Obama's organization has a big advantage six months out.

Iowa (6) — An important George W. Bush-state pick-up for Obama. Iowa has been a national popular vote bellwether for 20 years. Obama's attention in the state where his caucus victory launched him in 2008 is countered by Romney's two caucus campaigns. Conservatives are leery of Romney's Mormon faith and social issue profile, but he's got pro-business GOP Gov. Terry Branstad on his side.

New Hampshire (4) — Romney's backyard and vacation home. He won the 2012 primary big, but Obama peeled off this Bush state in 2008 and has worked hard to keep it. Vice President Joe Biden visited Friday. But the GOP is back in power in Legislature, and new Sen. Kelly Ayotte is seen as asset for Romney.

New Mexico (5) — New Mexico emerged as a swing state in the past decade. Democrat Al Gore, then Bush, then Obama carried it. An influx of Hispanic and younger voters has Obama team confident. Gov. Susana Martinez, a rising GOP star elected in 2010, gives the Romney team hope.

Nevada (6) — Part of a triad of Southwestern states Obama flipped in 2008. Nevada is also the prime example of the economy's struggles. Unemployment was 12.3 percent in February, a point Romney will press. There's a strong labor and Hispanic vote, a plus for Obama. A higher Mormon population helps Romney.

North Carolina (15) — Obama was the first Democrat to win North Carolina in 32 years and he hopes again to turn out a high percentage of newcomers and minorities. Romney is contesting the state, an outlier for Obama in 2008, aides say. Obama hopes that holding the party's national convention in Charlotte in September proves a boost.

Ohio (18) — The ultimate Midwestern swing state has been a general election bellwether since 1980. Romney won the 2012 primary and has support from establishment figures such as Sen. Rob Portman. Obama has the organizing advantage, although the economy remains a sticking point, especially in the industrial northwest.

Virginia (13) — Long a GOP bastion, Obama carried Virginia in 2008 by turning out young and minority voters. An influx of under-35 crowd, especially from the Washington, D.C., area, has continued. But Republicans roared back in 2010, ending consecutive Democratic administrations in governorship by electing up-and-comer Bob McDonnell.

LEANING REPUBLICAN (32):

Arizona (11) — 2008 GOP nominee John McCain's single-digit victory in his home state, and Hispanic and young voter boom, give Obama hope that Arizona is trending as others in Southwest. But Romney won big in February's primary, helped by the support of GOP Gov. Jan Brewer, in state where Republicans and the tea party are in charge.

Indiana (11) — Obama broke 44-year GOP trend by winning Indiana, albeit by barely a single percentage point. Unemployment is still high and the tea party is a new factor, both working against Obama.

Missouri (10) — Democrats have contested Missouri in the past three elections, only to lose each time. Democratic Sen. Claire McCaskill is in tough re-election bid, and Obama's approval has dipped below 40 percent.

SOLIDLY REPUBLICAN (159):

Alabama, Alaska, Arkansas, Georgia, Idaho, Kansas, Kentucky, Louisiana, Mississippi, Montana, Nebraska, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia and Wyoming.