Sen. Hillary Clinton took aim at Sen. Barack Obama Sunday after the Illinois senator told a crowd in Reading, Pa., that Clinton, Obama or GOP Sen. John McCain would all be better presidents than George W. Bush.
"You have a real choice in this election. Either Democrat would be better than John McCain - and all three of us would be better than George Bush," Obama said. "But what you have to ask yourself is, who has the chance to actually, really change things in a fundamental way?"
Clinton offered quick criticism of the quip during a campaign rally in rural Pennsylvania. "We need a nominee who will take on John McCain, not cheer on John McCain, and I will be that nominee," Clinton said.
Obama, who is leading Clinton in overall primary and caucus wins and elected delegates, took on his most negative tone of the race, calling her a compromised Washington insider during a campaign appearance on Sunday.
On Saturday, he accused Clinton of using "slash and burn" tactics like those used against her during her time as first lady.
"I'm thinking well, you learned the wrong lessons from those Republicans who were going after you in the same ways using the same tactics all those years," Obama told CBS News.
The battle was also waged on the airways. A new Clinton ad accuses Obama of taking almost 2 million dollars from lobbyists and corporate interests. Obama countered the claims in his own ad, denying taking money from special interests, but accusing Clinton of doing just that.
With shots flying back and forth, and all the money being poured into the race by the campaigns, a Sunday MSNBC/McClatchy poll showed little has changed in recent days, with Clinton holding a five point lead.
The lead is short of the wide margin Clinton was hoping would give her a resounding victory of both the popular vote and delegates to launch a final run at the nomination.
While the primary may prove a difficult one for Obama to win, his camp has been downplaying the importance of winning the Keystone State vote and aiming instead at winning delegates to maintain a lead and depriving Clinton of the momentum she is seeking.
But even if Clinton were to win by more than 20 percentage points tomorrow -- a highly unlikely scenario, polls show -- she would have a hard time catching up.
"The wheels would have to come off the Obama bus, and the engine would have to blow" Peter Fenn, a Democratic consultant who isn't affiliated with either campaign told Bloomberg news.
She would need "blowout numbers," Fenn said.
Still, Obama's efforts to court white voters in the Pennsylvania Democratic primary have been hurt by his recent comments on small town bitterness and other points of controversy, some residents of Muncy Valley, some 150 miles northwest of Philadelphia, told Reuters.
"He is saying people are weak, dumb and naive, and they are seeking religion as a way of getting through," Darwin Whitmoyer, 54, told the news agency. "He didn't help himself."
Obama has far outspent Clinton in Pennsylvania. Numbers released by his campaign Sunday showed he raised more than $42 million in campaign donations in March. Clinton campaign spokesperson Jay Carson told Reuters Clinton raised about $20 million.
With the money on Obama's side, for Clinton to have a chance at the nomination she will likely need to convince a majority of Democratic super delegates that it would be too risky to pick Obama to face McCain, according to AFP.
Clinton is hoping her message of electability will be reinforced tomorrow.
"I have carried the states that a Democrat must carry in order to win in November," Clinton told the Philadelphia Inquirer Sunday. "If you look at the electoral map, anything is possible, but it is more likely that the coalition I have put together is the winning coalition."