Top Democrats accused Republican White House hopeful Mitt Romney on Sunday of "cravenly" politicizing the deadly attack on the U.S. consulate in Benghazi to further his presidential ambitions.

The fallout from the attack has developed into a toxic political issue as Romney and Democratic President Barack Obama wage an all-out battle in a tight race 23 days out from the November 6 election.

Top Democrats accused Republican White House hopeful Mitt Romney on Sunday of "cravenly" politicizing the deadly attack on the U.S. consulate in Benghazi to further his presidential ambitions.

The fallout from the attack has developed into a toxic political issue as Romney and Democratic President Barack Obama wage an all-out battle in a tight race 23 days out from the November 6 election.

A shot was fired Friday at a campaign office for President Barack Obama in the western U.S. state of Colorado, shattering a window but injuring no one, police said.

Staff were in the office when the incident occurred mid-afternoon. "It looks like it was one shot that was fired into the structure," said Denver police spokeswoman Raquel Lopez, cited by The Denver Post.

U.S. President Barack Obama tried to steady panicking supporters Wednesday, insisting he would win re-election despite a "bad night" in a first debate in which he had been "too polite" to Mitt Romney.

"I got this," Obama said in a radio interview and predicted that Democratic "hand wringing" over his limp performance, which precipitated a polling slump, would be a mere memory after his next clash with Romney on Tuesday.

Inviting supporters to taunt Barack Obama with chants of "four more weeks," rival Mitt Romney surged into the lead in U.S. opinion polls Tuesday, his reward for beating the president in their first head-to-head debate.

With both candidates campaigning in perennial kingmaker state Ohio, top Obama aides put a brave face on the president's slide, insisting they had always known his re-election bid would be tough.

Barack Obama has "failed to lead" in the Middle East and the strained ties between his White House and Israel have emboldened Iran, presidential challenger Mitt Romney declared Monday.

In a major foreign policy speech, Romney warned the president's dithering had increased instability in a region clamoring for U.S. leadership and left both the United States and its Middle East allies less safe than they were.

Mitt Romney will call for a U.S. change of course in the Middle East on Monday, saying President Barack Obama's muddled strategy has failed to confront the challenges of extremism.

The Republican White House hopeful, offering a foreign policy vision that he and his campaign believe differs sharply from Obama's, said he would keep Iran in check, chase terrorists in Libya, put conditions on U.S. aid to Egypt and help arm Syrian rebels.

President Barack Obama has stashed $181 million into his re-election account to cheer supporters after his limp debate performance, but several polls show movement towards Republican Mitt Romney.

Obama's camp Saturday announced its biggest monthly haul of the 2012 race with its September fund-raising figures, a day after supporters got another fillip with news that the U.S. unemployment rate dipped below eight percent.

President Barack Obama on Thursday landed the verbal blows he missed the previous night in his debate with Mitt Romney, clawing at his Republican foe to stop him gaining a boost in the polls.

Obama went on the attack at big rallies in Colorado and Wisconsin and was energetic, combative and concise, the opposite of the tired and long-winded candidate who was decisively beaten by Romney on Wednesday night.

Mitt Romney regained momentum in the first debate by aggressively standing up to Barack Obama, analysts said, but it remains to be seen how much he can budge the needle in the White House race.

Obama spoke longer during the 90-minute showdown in Denver on Wednesday, but the Republican challenger landed more blows against an often-subdued president in their first of three debates ahead of the November 6 vote.