WASHINGTON — As Afghanistan grabs more of the political spotlight, the Republican presidential candidates are quick to criticize President Barack Obama's handling of the war. But they're struggling to explain how they would change the strategy they would inherit.

GOP front-runner Mitt Romney says Obama has exhibited "failed leadership" and should not have set a timetable for ending the war. But Romney won't say whether he would scrap the president's plans to bring the war to a close by the end of 2014.

Rivals Rick Santorum and Newt Gingrich have questioned whether the U.S. should be in Afghanistan at all, but neither has plans for withdrawing tens of thousands of American troops.

There may be concerns that detailed campaign promises could pigeonhole a candidate if he wins the White House.