Obama doesn't tell the truth, says Mitt Romney

Mitt Romney accused Barack Obama of a tendency to "say things that aren't true" on Friday, as the Republican challenger came under mounting pressure from a series of polls that showed him trailing in key battleground states.

After a week in which Romney was criticised by members of both parties for political point-scoring, following the death of the US ambassador to Libya, Chris Stevens, the former Massachusetts governor said he was now looking forward to locking horns with Obama in next month's first presidential debate.

"I think the challenge that I'll have in the debate is that the president tends to - how shall I say it? - say things that aren't true," he told ABC News. Speaking about how to tackle his opponent, Romney said he did not know whether he would spend his time "correcting things that aren't quite accurate" or "talk about the things I want to talk about".

Although Romney is trailing Obama by just 3.2% nationally, a poll on Friday showed him trailing dangerously in the pivotal swing states of Ohio, Florida and Virginia. Analysts said he must win at least two of the three states if he is to win. According to the survey, Obama was up seven points in Ohio (50-43), five in Virginia (49-44) and five in Florida (49-44).

The Romney campaign said the survey, which was taken after the Democratic Convention, reflected the "bounce" Obama was expected to get, and predicted that the weak economy would narrow the gap as election day approached.

Romney said he was unconcerned, predicting that polls would "bounce around" a lot before November 6.

He also risked giving fresh ammunition to Democrat attempts to paint him as an elitist, by describing middle income as people earning $250,000 or less (154,000 pounds), five times the US median income of $52,000 (32,000 pounds).

However, his supporters pointed out that Obama used the same $250,000 threshold to separate ordinary earners from the "rich" - on whom, unlike Republicans, he wants to raise taxes.

On the campaign trail, Romney has returned his focus to the economy, although he attempted to take back some ground on foreign policy, sending out surrogates to argue that the Middle East protests would not have happened under a Romney administration.

Richard Williamson, a key adviser for Romney, compared Obama's international leadership to Jimmy Carter's, under whose presidency the last US ambassador was assassinated. He accused Obama of failing to nurture a proper relationship with Egypt's new government and said Romney would have taken a tougher line with Iran, been quicker to arm Syrian rebel groups and demanded more of Egypt's new government in return for US financial support.

In reply, the Obama campaign accused Romney of trying to "shamelessly politicise a sensitive international situation" while demonstrating that he was "not at all prepared" to manage the kinds of crises faced by a US president.