HEMPSTEAD, N.Y. - While President Obama is claiming victory in Tuesday's contentious presidential debate, polls suggest Mitt Romney scored points with viewers in a way that could boost his already growing momentum.

Gallup on Wednesday released a poll that for the first time showed Romney with a 6-percentage-point lead over Obama -- an advantage that falls outside the possibility of polling error and clearly shows Romney taking over as the frontrunner just three weeks out from Election Day.

The poll is an accumulation of data over several days and does not take into account voters' views of the debate slugfest. Moreover, snap polls taken immediately after the second debate show a majority of viewers clearly believe Obama won. Still, Romney now holds a substantial lead over Obama on the question of who would best handle the economy, a pivotal issue in the campaign. A CNN poll put Romney's advantage on that issue at 18 percentage points. On the issue of taxes, the poll shows Romney with a 7-point advantage.

"I believe the momentum is still with Romney," Republican strategist Brad Blakeman told The Washington Examiner.

Sen. Rob Portman, R-Ohio, who served as Romney's sparring partner to prepare him for Tuesday's debate, acknowledged that Obama was more aggressive than he was in their first debate on Oct. 3. The president's performance energized his Democratic supporters, many of whom were growing despondent over his earlier listless performance. But Portman said it probably wasn't enough to sway undecided voters.

"If you are an undecided voter, what did you hear from Barack Obama about the future?" Portman said. "You heard virtually nothing."

Romney, Portman said, talked specifically about "new fresh ideas, pro-growth ideas, to get this economy going again."

"If you are an undecided voter," Portman said, "that is what you want to hear."

Despite Republicans' confidence, Democrats said Obama's combative posture in the latest debate will help him win back the momentum as the race enters its homestretch.

"I think the president has more than recovered," said Rep. Chris Van Hollen, D-Md. "Now the president will begin the bounce back."

Peter Brown, assistant director of the Quinnipiac University Polling Institute, told The Examiner that whatever Romney or Obama gained in the debate will take time to register in the polls,

"Clearly, debates can shift numbers," Brown said, "but the important thing to know is you need to wait a few days to see what the numbers are."

Brown believes those polling measurements will be more accurate by the end of the weekend.

Romney and Obama will face off for the third and final time on Monday in Boca Raton, Fla.