New political surveys in the U.S. show that President Barack Obama has, at least for the moment, edged ahead of Republican Mitt Romney as the two candidates enter the final eight weeks of the country's presidential election campaign.

The two candidates had been virtually tied in surveys a week ago after completion of Mr. Romney's national Republican convention. But after Mr. Obama accepted the Democratic nomination for a second term as president at his party's convention last week, four polls showed his support increasing.

U.S. presidential candidates frequently get a “bounce” of support after their national conventions, but Mr. Obama's appears to be more substantial than Mr. Romney's. Sometimes such gains prove to be short-lived, but not always.

Two prominent polls tracking voter sentiment over several days — the Gallup and Rasmussen Reports surveys — showed the president with his biggest lead in several weeks. The Gallup poll on Sunday showed an Obama lead of 49 percent to 44, with Rasmussen at a similar 49-45 count.

The candidates are focusing their campaigning on key states where the surveys show voter sentiment is virtually split between the two. The U.S. does not elect its presidents by popular vote, but rather through an electoral college system in which each state's influence on the outcome is weighted by its population.

Mr. Obama's re-election campaign, for the first time in several months, narrowly out-raised Mr. Romney's fundraising effort in August.

Mr. Obama's campaign manager, Jim Messina, said Sunday the campaign had pulled in $114 million last month in conjunction with the Democratic National Committee. Hours earlier, the Romney campaign announced it had raised $111 million in August along with the Republican National Committee.

Although Mr. Romney was out-raised in August, it was the third straight month his campaign had collected more than $100 million and he has more cash in the bank than the president, as they head to the November 6 election.