Clinton is now running a television ad attacking the remarks, which Obama made last week at a San Francisco fundraiser.
Franklin & Marshall pollster G. Terry Madonna agreed that the "bitter" fallout may still be shaping the race.
"The question is if [Clinton] has stopped Obama's surge permanently," said Madonna. "With the new commercial and the San Francisco statements, can she push the lead back to double digits?"
A new poll from Quinnipiac University yesterday also showed Clinton leading by just 6 points.
Madonna said that Obama has been gaining ground in the past month with his statewide tour and television blitz.
"Until the past weekend, he had four commercials, she had two," Madonna said. "The voters say his commercials are more effective."
Clinton also lost some ground with negative campaigning and the coverage of her inaccurate "sniper fire" comments about her 1996 visit to Bosnia, Madonna said.
The poll also showed a clear divide between the eastern and western parts of the state, he said. Western Pennsylvania, older and more conservative than the eastern part, is strong Clinton country. The southeast and Philadelphia, more liberal and affluent, are feeling Obama-mania.
Obama led in Philadelphia 50 percent to 34 percent, among likely voters. And in southeastern Pennsylvania Obama was ahead 51 percent to 38 percent.
Clinton was favored by 59 percent of northwestern Pennsylvania likely voters to 28 percent for Obama. She also led Obama 59 percent to 18 in the Southwest.
The regional difference will play a key role in the results Tuesday, according to Madonna.
"What matters will be the turnout by these regional differences — which voters are more excited," Madonna said.
Perceptions of the candidates have shifted slightly since March. Clinton's favorable ratings among registered voters have declined. She is now at 58 percent favorable, down from 65 percent. Obama's favorables have risen from 47 percent in March to 53 percent now.
On issues, the economy was cited as most important by 43 percent of registered voters. The Iraq war came next with 23 percent of voters and then health care with 13 percent.
On the idea of a shared ticket, Clinton supporters were more into it than Obama backers. Among Clinton voters, 43 percent supported making Obama her vice president. But only 30 percent of Obama fans thought that he should choose Clinton as his VP.
More voters thought that the news media have been harder on Clinton than Obama, with 39 percent saying Clinton gets rougher treatment and only 5 percent saying that the media are harder on Obama. But 53 percent said the two were treated the same.
And after outspending Clinton, Obama has reached more voters with his TV ads. A whopping 94 percent of voters have seen Obama ads. But Clinton is not far behind, reaching 88 percent of voters with her ads.
Obama's ads seem to resonate more with voters. Asked whose ads are the more effective, 46 percent said Obama while only 24 percent said Clinton.
Among likely voters, Clinton won 50 percent of the white vote to 36 percent for Obama. Among non-whites, Obama led 67 percent to 19 percent.
Clinton led among union members 44 percent to 33 percent — and among Catholics — 59 percent to 25 percent.
Obama led among Protestant voters, with 43 percent to Clinton's 40 percent. And he took 47 percent of voters with a college degree, while Clinton got 41 percent.
Also, suggesting that Obama has successfully registered new voters, 60 percent of people registered in the past six months said they were supporting Obama, compared with 37 percent for Clinton.
For complete poll results, visit http://go.philly.com/aprilpoll. *
Daily News reporter Dave Davies contributed to this report.