Obama Tries to Hold Off Favored Clinton in Pa.

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Obama Courts Crowds, Criticizes Clinton in Whistle-Stop Tour

Sen. Barack Obama drew enthusiastic crowds Saturday on a train tour from Philadelphia to Harrisburg, Pa.

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"The Obama campaign is outspending us three-to-one in Pennsylvania. But I'm confident we can win in Pennsylvania, and I know Hillary is too," Garin wrote. Clinton campaign aides said that at least 7,000 volunteers are actively working in the state, whose eight largest media markets are now saturated with ads.

Each is also seeking to poach from the other's base. Obama spent much of the weekend touring Clinton country, in Erie, Williamsport, Scranton and the like, while Clinton was scouring the Philadelphia suburbs and kicked off her final push in Haverford, with her mother and daughter, on Thursday. Clinton holds significant advantages in the state, including its large population of older, lower-income voters who have proved loyal to her in other contests and the backing of both Rendell and Philadelphia Mayor Michael Nutter.

Rendell has practically taken over the role of Clinton campaign manager in Pennsylvania, advisers said, spending an extraordinary amount of time toward turning his political machine into a primary operation.

But Obama has invested heavily to make up ground, using his big financial advantage to air up to $3 million per week worth of television ads. He has two high-profile surrogates, Casey and Rep. Patrick J. Murphy, a freshman Democrat from the Philadelphia suburbs.

He has also carried most key newspaper endorsements, including from the Philadelphia Daily News and the Pittsburgh Post-Gazette.

The outcome Tuesday could be decided in certain swing regions. One is the Lehigh Valley, anchored by Allentown and home to about 150,000 Democrats of all varieties. Another is south-central Pennsylvania, including Lancaster, York, Lebanon and Cumberland. This region counts around 400,000 Democrats, also of various demographic profiles and who follow unpredictable voting patterns. The city of Lancaster, for instance, is a progressive antiwar oasis, tucked inside a more conservative county known for its large Amish population.

"It's like a chessboard. Each of the pieces plays a certain role," said G. Terry Madonna, a pollster and political science professor at Franklin & Marshall College in Lancaster. Based on the Democratic voter population, Madonna estimated that Clinton holds a natural advantage in the state of six to nine percentage points.

Barring a surprise win by Obama, the campaign is poised to shift immediately on Tuesday evening to its next playing field: Indiana and North Carolina, where Democrats will go to the polls on May 6.

Staff writer Perry Bacon Jr., traveling with Clinton, contributed to this report.