Can Mitt Romney sustain the momentum he gained from the debate?

Mitt Romney's poll numbers have improved since last week's debate, as indicated Monday by a Gallup tracking-poll release. Still, a couple of things could still be in President Obama's favor.

The polls keep coming, and the news is consistent: Thursday night was a good night for Mitt Romney.

However, it's unclear how permanent that bounce is and whether the race has truly been reshaped.

Perhaps the best news for Mr. Romney came with Monday's Gallup tracking-poll release. While the poll still shows President Obama having an edge of three percentage points among registered voters, the result is dramatically different when Gallup isolates the pre- and post-debate interviews. (The tracking poll gives seven-day rolling averages.)

In the interviews conducted before the debate, Mr. Obama had a five-point lead over Romney. In the three days of interviews conducted after the debate, the two candidates were tied, each with 47 percent of registered voters.

"The first presidential debate went decidedly in Romney's favor," Gallup wrote in its poll analysis. "The debate appears to have affected voters to some degree, given the narrowing of the race in the three days after the debate compared with the three days prior."

Then the analysis notes, "Still, the impact was not so strong that it changed the race to the point where Romney emerged as the leader among registered voters. Rather, at least in the first three days of Gallup tracking after the debate, the race is tied."

With last week's debate, Gallup registered the most decisive debate win ever, with those who watched the debate overwhelmingly judging Romney the winner, 72 percent to 20 percent. Prior to this 52-point win, the largest margin that Gallup had ever measured in gauging viewers' debate reaction was a 42-point win for Bill Clinton over George H.W. Bush in a 1992 town-hall debate.

A Politico/George Washington University battleground tracking poll of likely voters that was released Monday also indicates potential problems for Obama – particularly with voters' enthusiasm levels.

The poll shows Obama with a one-point lead over Romney (a statistical tie) – one point closer than a week ago. But more of those who back Romney say they are "extremely likely" to vote (86 percent) compared with those who support Obama (73 percent).

Beyond that, more Republicans than Democrats say they are extremely likely to vote – a potential problem for Obama given the consistent tightness of the race. Among voters who rate themselves as "extremely likely," Romney beats Obama, 52 percent to 46 percent. Three weeks ago, Obama led with that group of voters, 50 percent to 47 percent.

So, where's the good news for Obama in all this?

For starters, the surprisingly good jobs numbers this past Friday seem to have muted the effect of the debate at least somewhat.

Also, the fact that the various tracking polls – all of which keep replacing one day of pre-debate polls with another day of post-debate ones – haven't continued to get markedly better each day "can be read as mildly disappointing for [Romney]," notes polling maven Nate Silver of The New York Times in his FiveThirtyEight blog.

Mr. Silver acknowledges Romney's very strong performance – and says his own forecasting model, which now gives Romney just over a 21 percent chance of winning the electoral vote, may be underestimating his chances and the effect of the debate. But he also says that bounces like the one Romney received are sometimes ephemeral.

"[S]ome changes may be real, but short-lived," Silver writes. "It seems quite possible that Mr. Romney would have had at least an even-money chance of winning an election conducted on Thursday exactly, when his polling was very strong – but there was apparently less strength in his numbers on Saturday."

Romney clearly gained some much-needed momentum from his performance Wednesday night. Now the question for poll-watchers is whether he can sustain it over the coming weeks.