Romney is now viewed positively by 51 percent of voters, the first time the Republican challenger has enjoyed a net positive in the presidential race. Obama's favorability rating remained unchanged at 56 percent.

Romney moved ahead of the president on several core issues after the Wednesday debate, which was widely seen as a victory for the Republican candidate.

Voters now see Romney as a better bet to boost the economy, spur job creation and manage the budget deficit, the poll found. He narrowed Obama's advantage on taxes, Social Security and the Medicare health plan for retirees.

Debates generally do not have a big impact on the outcome of presidential elections, but Romney's strong performance could make the race more competitive, Ipsos pollster Cliff Young said.

"If he has more debates like this, is able to push through his message and target undecideds, we might see movement in voting intention, but he needs a lot more of this," Young said.

The poll found that Obama's seven-point advantage over Romney had narrowed to a five-point lead, 48 percent to 43 percent, but a truly accurate reading on the debate's impact will not be possible for several days, he said.

That is because the poll drew on a smaller pool of voters, taken over a shorter period of time, than the Reuters/Ipsos daily tracking poll that measures the prospects of each candidate.

The online poll surveyed 536 registered voters on Wednesday and Thursday after the debate. It has a credibility interval of 4.8 percentage points.