SALT LAKE CITY — Sen. Mike Lee endorsed Texas Sen. Ted Cruz on Thursday, making him the first U.S. senator to back Cruz's bid for president.

Lee made the announcement in Miami ahead of Thursday night’s Republican debate. Miami is the hometown of Sen. Marco Rubio, R-Fla., whose presidential campaign is on life support.

The Utah Republican said there are a number of reasons to get behind Cruz, but they boil down to one thing: "We've reached a point when we need to unite behind a single candidate," he told reporters.

Cruz is the only GOP candidate who can beat Donald Trump and Hillary Clinton, Lee said.

There's a big difference between confusion and confidence, platitudes and a plan, and slogans and substance, "and Ted is that difference," he said.

Lee held off on backing a candidate because he said he didn't want to have to choose among his close friends in the Senate. That list of GOP conservatives also included Kentucky Sen. Rand Paul until Paul ended his campaign.

The Utah Republican, who faces re-election next year, has joined Cruz in a number of political battles in Congress, most memorably a fight over the Affordable Care Act that led to a federal government shutdown in 2013.

A year ago, Lee and Cruz were cheered at a Utah Republican rally in Sandy where Cruz called Lee a "rock star" and Lee told the crowd that some in Washington don't like those who "push back" against the establishment.

Cruz said he couldn't be more humbled by Lee's endorsement.

"Mike is a brilliant policy entrepreneur who has been a driving force in promoting conservative reforms to lift people out of poverty, make education more affordable, and fix our tax system," he said in a statement. "I am privileged to have his support and look forward to having his help coalescing conservatives around our campaign.”

All but one of Utah's congressional delegation have thrown their support behind Rubio. Sen. Orrin Hatch, R-Utah, had backed former Florida Gov. Jeb Bush.

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