Polls are showing GOP nominee Mitt Romney has a slight lead in national polls  in the weeks prior to Election Day. (Blade file photo by Michael Key)

New polling data in the presidential race following last week’s debate is giving Democrats heartburn, suggesting that President Obama may not coast to victory on Election Day as many observers previously predicted.

On Tuesday, two national polls were published giving Republican presidential nominee Mitt Romney a narrow lead over Obama. A report from Public Policy Polling found the GOP candidate had support from 49 percent of likely voters in the poll, compared to 47 percent for Obama. A Gallup tracking poll published on the same day had identical results.

Hilary Rosen, a lesbian Democratic activist and commentator, said Democrats “of course” should be concerned that Obama is facing a challenging road to re-election, but she remained optimistic.

“This race was always going to be decided by 1 or 2 points,” Rosen said. “Everyone in the D.C. Metro area can help by making sure the president wins in Virginia. I am confident that we [will] have another Obama rebound story coming in the next few weeks.”

The polling was conducted in the days after the Denver presidential debate, in which most observers believed Romney bested Obama — despite making controversial comments about cutting the federal subsidy for PBS as well as apparently altering his views on tax cuts for the wealthy and barring insurance companies from discriminating on the basis of pre-existing conditions.

The Tuesday polls came the day after the Pew Research Center published a poll giving Romney a 4-point lead over Obama among those most likely to vote. Just last month, the same poll gave Obama an 8-point lead over Romney. Other polls this week from Rasmussen, Reuters and Zogby have the race in a dead-heat.

The Pew results received significant attention because they were the first to place Romney ahead of Obama and because the same pollster had previously given Obama a wide lead. But the report was also seen as an outlier because — as pointed out by Electoral Vote Predictor — the internals of the poll are questionable.

In the October sample, 31 percent of respondents identified as Democrats, compared to 39 percent in September. Conversely, 36 percent of respondents identified as Republicans in October compared to 29 percent in September. Consequently, Pew may have undersampled Democrats and oversampled Republicans.

Richard Grenell, who’s gay and briefly served as the Romney campaign’s foreign policy spokesperson, said he doesn’t “put much stock in snapshot polls,” but believes Romney could win the election based on anecdotal evidence he’s heard from people unhappy with Obama.

“I’ve always known the American people are frustrated and disappointed with President Obama’s disastrous leadership both domestically and globally,” Grenell said. “Sadly, President Obama has failed to unite the country and has been one of the most divisive leaders the U.S. has ever seen. I keep hearing from people that voted for Obama in 2008 who will be voting for Romney now. Romney has a real chance.”

In polls taken in battleground states, the race is similarly showing signs of tightening. An American Research Group poll published Tuesday gave Romney a narrow lead in two swing states. In Colorado, the poll gave Romney a lead of 50 percent compared to the 46 percent of respondents who favored Obama, although three percent were undecided. In Ohio, Romney edged Obama by a 48-47 margin with four percent of voters identifying as undecided.

Still, the news was good for Obama in other polls for key battleground states. Contrary to American Research Group results for Ohio, a CNN/ORC poll gave Obama a significant lead in the state, placing him ahead of Romney, 51-47.

According to a Siena poll published Tuesday, Obama still enjoys a lead over Romney in Pennsylvania. Obama was favored by 43 percent of likely voters in the Keystone State and Romney has the support of 40 percent — although 12 percent were undecided.

Dan Pinello, who’s gay and a political scientist at the City University of New York, said the changes in the polls reflect the volatile nature of public opinion over the course of the presidential campaign season.

“Thus, the best answer now about whether the first debate succeeded in salvaging Romney’s campaign — and whether Barack Obama’s lackluster performance snatched defeat from the jaws of victory — is:  It’s too soon to know for sure,” Pinello said. “At least another week of polling data is necessary for any certainty.”

The next test for the presidential campaign could be the debate between Vice President Joseph Biden and Republican vice presidential nominee Paul Ryan on Thursday at Centre College in Danville, Ky. Two more presidential debates between Obama and Biden — one a town hall discussion at Hofstra University on Oct. 16 and another a foreign policy debate at Lynn University in Florida on Oct. 22 — are set to take place before Election Day.

Pinello maintained incumbent presidents often come back after first debate performances that are regarded as poor — recalling John Kerry’s perceived win over George W. Bush in the first debate of 2004 as well as a first debate in 1984 when President Reagan was regarded to have fared poorly against Democrat Walter Mondale.

“In both instances, the incumbents did better in subsequent debates, and voters apparently gave them any benefit of the doubt,” Pinello said. “Indeed, incumbent presidents have inherent advantages. They are known commodities to voters, while challengers necessarily represent a political roll of the dice.”

If Biden triumphs in the vice presidential debate, Pinello said the rise in popularity for the Romney-Ryan ticket could diminish as quickly as it emerged. But Pinello issued a warning to Democrats if more poor debate performances follow.

“Needless to say, if Ryan trounces Biden on Thursday, then all bets are off,” Pinello said. “Progressives should contemplate what life in Canada might be like.”