Hoping to distinguish themselves from the other before the Potomac primaries, Clinton and Obama took swipes at each other the day before the vote.
Clinton accused Obama of suspicious activity with a contributor.
"Sen. Obama has some questions to answer about his dealings with one of his largest contributors, Exelon, a big nuclear power company; apparently he cut some deals behind closed doors to protect them from full disclosure of the nuclear industry," she told ABC News' Washington affiliate WJLA Monday night.
Obama took a swipe at Clinton's campaign shakeup and news last week that the senator had injected $5 million of her own money into her campaign in January.
"I started from scratch and was up against an operation that had been built over the course of 20 years by a former president with the bulk of the Democratic establishment on their side and after setting up a hundred-million-plus operation with hundreds of employees around the country; it looks like we've played them to a draw so far," Obama said.
"I think that gives you a sense of how we run a campaign. There hasn't been a lot of drama in my campaign. You haven't seen a lot of turnover in my campaign."
Despite Obama's surge, neither candidate may crush the other in the upcoming primary and caucus contests given the proportionality rules of the Democratic Party primaries -- setting up a scenario in which the nomination fight spills onto the convention floor in August.
There, superdelegates -- 796 state party leaders, national party leaders and former Democratic presidents who get to act as free agents at the party's convention able to back any candidate they wish -- would hold the power.
While most of the superdelegates are sitting on the fence, Clinton is leading Obama among the superdelegates who have decided whom to support, according to ABC News' latest survey.
Obama has emphasized his belief that it would be unfair if the Democratic contest was decided by superdelegates.
"We've got to make sure that whoever wins the most votes, the most delegates, that they are the nominee," he told ABC news affiliate WJLA Monday.
"I think that would be problematic if either Sen. Clinton or myself came in with having won the most support from voters and that was somehow overturned by party insiders."
ABC News' Kate Snow, Ron Claiborne, Gary Langer, Karen Travers, Tahman Bradley, and Sunlen Miller contributed reporting.