Both sides are on the attack and arguing about who is guilty of the most outrageous distortions in a last-minute wave of television ads, speeches, and interviews. Obama, a senator from Illinois, says Clinton is beholden to Washington's special interests and won't be able to get an equitable healthcare plan approved. Clinton, a senator from New York, says Obama's healthcare plan wouldn't cover all Americans and that he is too inexperienced to serve as commander in chief.
A new MSNBC/McClatchy/Pittsburgh Post-Gazette poll, conducted Thursday and Friday, showed Clinton ahead of Obama 48 to 43 percent. Many voters remain undecided, and Obama is thought to be surging among new voters and young people, a trend that has occurred in other states. But Clinton's strength among working-class and lower-middle-income voters and older women could put her over the top.
The final days have seen a nasty duel that only intensified as the balloting approached, with each side accusing the other of unfair attacks. "Senator Obama has once again used a negative and misleading ad about Senator Clinton's healthcare plan that has been debunked as false repeatedly," says Irwin Redlener, national chairman of Doctors for Hillary. "We need leadership and action, not negative attacks and empty rhetoric."
The Obama campaign says Clinton is distorting his record on healthcare, fighting special interests, and other issues. "Eleventh-hour smears, paid for by lobbyist money: Isn't that exactly what we need to change?" asks Dan Pfeiffer, an Obama spokesman, echoing a line from an Obama TV ad.
Obama has far outspent Clinton on TV commercials in Pennsylvania, $8.1 million to $3.2 million, in recent weeks, according to the Campaign Media Analysis Group, which studies ad expenditures.
Tuesday's primary will begin the final phase of the Democratic campaign, with 10 remaining contests for delegates to the national convention in Denver this August. Next up will be the Guam caucuses on May 3 and the Indiana and North Carolina primaries May 6. Obama is favored in all three.
Obama leads in delegates, according to the Associated Press, 1,646 to Clinton's 1,507, with 2,025 needed for the nomination. If no one gets a majority from the primaries and caucuses, as expected, about 800 "superdelegates"—elected Democratic officials and activists—will determine the outcome.
John McCain, a senator from Arizona, has locked up the Republican presidential nomination.