Sen. Barack Obama (D-Ill.), at the end of a six-day bus tour of Pennsylvania, might be putting himself in a position to upset state front-runner Sen. Hillary Rodham Clinton (D-N.Y.) in the Keystone State, a turn of events that would essentially end the Democratic nomination fight, analysts say.

Clinton has long held sizable winning margins in polls leading up to the April 22 Pennsylvania primary. Support from the state’s major Democrats has coalesced behind her following the endorsements of Gov. Ed Rendell and Philadelphia Mayor Michael Nutter.

While most analysts still think Pennsylvania is Clinton’s to lose, the possibility of Obama pulling off an upset — or merely defying expectations — doesn’t seem as far-fetched as it did just a week ago.

Most polls continue to show Clinton with big leads, and the RealClearPolitics average of polls shows Clinton up by 15 points. But a new poll by Rasmussen released Tuesday morning, as Obama entered the fifth day of his statewide tour, showed a dramatic shift, with the Illinois senator closing in on Clinton, 47 percent to 42.

The Rasmussen poll shows Clinton’s lead cut in half from just a week ago, and a SurveyUSA poll also released Tuesday showed Clinton’s lead shrinking from 19 to 12 percentage points.

The Obama campaign is continuing to push the narrative that Clinton is the expected winner of the state.

“The Clinton campaign has said she is unbeatable in Pennsylvania, so obviously this is an uphill climb,” Tommy Vietor, an Obama spokesman, said in an e-mail. “But despite the fact that she has so much of the state’s institutional support, we’ll continue to compete there and hope to do well.”

And given the large leads the New York senator held from the time the focus shifted to Pennsylvania, analysts agree that a single-digit win for Clinton would actually be viewed as a loss.

“If she loses, it’s over. I mean it’s flat-out over,” said Terry Madonna, a political analyst and pollster at Franklin and Marshall College. “And if he gets her into single digits, it weakens her case.”

Madonna said Clinton needs a big win in the state to gain ground on both the delegate count and the overall popular vote. Given the realities of the Democratic system of proportioning delegates and Obama’s strengths with different demographics, moving either number presents a significant challenge.

“If she wins by 10 points, I think that’s probably all she has to do to claim a big victory,” Madonna said.
Jamal Simmons, a Democratic strategist supporting Obama, said Clinton should win the state handily given her “institutional” strengths, but if Obama is able to close within seven points, then “that’s an upset.”

Simmons, who called Obama’s chances of winning the state “remote,” said he doesn’t see anything happening in Pennsylvania to make him think the race won’t continue through the end of the primaries.

“I think this campaign goes until June 3 unless there’s a serious upset,” Simmons said. “If he wins Pennsylvania, I think we’re having a very different discussion.”

Clinton is maintaining a lead despite being outspent in the state by a ratio of 5 to 1, something Simmons said doesn’t happen unless a campaign is in financial trouble.