President Barack Obama gained ground on Mitt Romney for the third straight day in the Reuters/Ipsos daily national tracking pol. He had a 46 to 43 percent lead on Tuesday.

Released hours before the second debate, the poll showed that the number of undecided voters had increased, indicating a falling off of gains Romney had made among the coveted voting bloc last week.

The poll showed that Obama has recovered some ground after a poor showing in his first presidential debate. After dropping below Romney in the wake of the Oct. 3 debate, Obama regained the lead on Sunday and has increased that by 1 percentage point each day this week.

"I think what we're seeing is after the first debate Romney definitely saw a surge. A lot of his surge wasn't coming from Obama voters, it was coming from undecided voters, which is exactly where both candidates are seeking support," Ipsos pollster Julia Clark said.

"Now, we've actually seen the Romney bump decrease again a little bit," Clark said.

She said the number of people who have changed their minds and moved back to the undecided column took 2 percentage points off Romney's support and one point from Obama. Undecided voters now account for about 13 percent of likely voters, compared with 10 percent on Monday.

The online survey of 1,846 likely voters was conducted between Friday and Tuesday.

Obama also gained a little in the IDB/TIPP daily tracking poll released Tuesday, leading Romney by 47.3 to 45.7 percent.

In contrast, Romney was ahead in Tuesday’s daily Gallup tracking poll among likely voters by 50 to 46. The two presidential candidates remain tied among registered voters, with 47 percent each.

In Pennsylvania, which the Republicans appeared to be conceding a few weeks ago, Romney seems back in the race after the first debate, Talking Points Memo reports.

On Monday, a poll from Muhlenberg College showed Romney trailing by just 4 percent among likely Pennsylvania voters. That’s a shift from September, when Muhlenberg found Romney down by 7 percentage points. Then on Tuesday, a poll from Quinnipiac University also showed Romney trailing by 4, up from a 12-point deficit in September.

The trend may be affecting the Pennsylvania Senate race, too. Democratic Sen. Bob Casey leads by only three points over his Republican challenger, businessman Tom Smith, in a new poll released Tuesday morning by Quinnipiac, CBS News and the New York Times. Casey had been far ahead in earlier surveys.