Obama leads 48 per cent to 45 per cent in a CNN Poll of Polls, a sample of three recent national surveys of the presidential race that culminates in November.
While Romney has outpaced Obama and the Democrats on fundraising, the campaign for the incumbent's re-election has intensified its attack on the challenger, and its efforts to paint Romney as a corporate outsourcing specialist appear to be having an impact on swing voters.
The CNN Poll of Polls uses three recent surveys -- CNN/ORC International Poll, the Gallup Daily Tracking Poll, and the Newsweek/Daily Beast Poll, to arrive at a consolidated figure of 48 to 45.
In the most recent CNN/ORC International Poll, conducted between June 28 and July 1, Obama is ahead of Romney, 49 per cent to 46 per cent.
The Gallup poll includes results of the past seven days and has Obama over Romney, 48 per cent to 44 per cent.
In the Newsweek/Daily Beast poll, meanwhile, Obama leads Romney 47 per cent to 44 per cent.
More From This Section
Obama's lead, however, in all three polls was close to the sampling error limit of two to 2.5 percentage points.
However, the CNN poll also showed Romney with an advantage over Obama in the 15 states listed as 'battlegrounds' on the CNN Electoral Map.
Romney was ahead of Obama 51 per cent to 43 per cent in those states, including those that are leaning but not solid for Obama or Romney and those which appear to be true tossups, CNN said.
Political sparks have been flying in the US as the two camps have intensified attacks against each other, taking bitter taste at times.
Ahead of the November election, the Obama campaign has been portraying Romney as a "pioneer" of outsourcing to low-wage countries like India and China, to counter Romney's claims that he was the right man to fix America's economy.