WASHINGTON — US President Barack Obama has done a good job in battling Islamist extremism, accomplishing more than predecessor George W. Bush in Pakistan's tribal areas, Republican House Speaker John Boehner said Thursday.

"I think so far the president's done just fine," Boehner, one of Obama's most fierce critics, said one day before Republican White House hopeful Mitt Romney was expected to attack current US foreign policy in a speech.

"I think that when you look at the prosecution of the war effort against the enemy in the tribal areas, there's clearly more been done under President Obama than it was under President Bush, in terms of a more aggressive effort focused at them," Boehner said at a Washington conference.

The speaker had been asked whether Obama -- on whose watch the United States has killed Al-Qaeda mastermind Osama bin Laden and radical US-born Islamic cleric Anwar al-Awlaqi, a top figure in Al-Qaeda in the Arabian Peninsula -- had proven to be more effective than Bush.

Romney, who announced his top diplomatic and national security advisers on Thursday, was to follow up Friday with a speech laying out his foreign policy vision and was expected to assail Obama's approach.

The former Massachusetts governor has retaken the lead from Texas Governor Rick Perry in the race for the party's nomination to take on Obama in the November 2012 election.