Having begun the 2012 election without strong feelings towards his Republican rival, Obama has reportedly grown to despise him and now subscribes to one of the most common criticisms of the former Massachusetts governor: that he stands for nothing and will say anything to get elected.

"There was a baseline of respect for John McCain. The president always thought he was an honourable man and a war hero," one of Obama's advisers is quoted as saying in Obama's Last Stand, a forthcoming book. "That doesn't hold true for Romney. He was no goddamned war hero."

White House aides were reportedly relieved as the president began to voice his contempt for Romney, believing they could channel his anger on the campaign trail and keep Obama motivated throughout the brutal election.

In his first election rally, Obama described his opponent as "a patriotic American who has raised a wonderful family". But since then he has done nothing to curb personal attacks on Romney by his staff or other Democrats.

Stephanie Cutter, Obama's 2012 deputy campaign manager, speculated last month that the Republican candidate might be personally guilty of a felony by improperly filing business records.

She later refused to apologise for the unsubstantiated claim.

Early in the election - cautious that Obama remained personally popular even as his job approval ratings had slumped to below 50% - Romney would regularly describe his opponent as "a nice guy" who was out of his depth.

His rhetoric has become significantly harsher as the general election approaches, accusing Obama of cronyism and trying to warp American society into a "European-style" collectivist state.

The two White House contenders are believed to have only met twice and each time very briefly.

By contrast, Obama spent long hours in the Senate with both McCain and Hillary Clinton.

Romney is unlikely to be fazed by reports of the president's dislike for him and will instead take encouragement from figures showing he raised more money than Obama for a third straight month in a row. - ©The Daily Telegraph