-LRB- CNN -RRB- -- Sen. Hillary Clinton on Thursday sharpened her attacks on Democratic rival Sen. Barack Obama as she faces what even her supporters admit are must-win situations in Texas and Ohio in the weeks ahead . At a campaign stop at a General Motors Corp. plant in Youngstown , Ohio , the senator from New York accused Obama of caving in to special interests . `` My opponent says that he 'll take on the special interests , '' she said . `` Well , he told people he stood up to the nuclear industry and passed a bill against them . But he actually let the nuclear industry water down his bill -- the bill never actually passed . '' Clinton was referring to a 2006 bill that Obama drafted after an Illinois nuclear power plant was found to have released radiation into surrounding groundwater . Obama 's original bill would have required power plants to notify the public and government officials when any radiation was released , but subsequent versions had less stringent reporting requirements , The New York Times reported . The bill was never voted on by the full Senate . Clinton also accused Obama of supporting `` billions of dollars of breaks for the oil industry '' by voting for an energy bill she opposed and said he did not support the workers of a Maytag Corp. plant that closed in his home state of Illinois . Watch Clinton attack Obama '' Reacting to Clinton 's charges , Obama spokesman Bill Burton said his candidate `` does n't need any lectures on special interests from the candidate who 's taken more money from Washington lobbyists than any Republican running for president . '' `` Sen. Clinton may have said that attacks and distortions are the ` fun ' and ` exciting ' part of the campaign , but they 're exactly what everyone else in America is tired of , '' Burton said . In recent days , Clinton has challenged Obama 's ability to deliver on his rhetoric . `` There 's a big difference between us -- speeches versus solutions , talk versus action , '' she said . `` Speeches do n't put food on the table . Speeches do n't fill up your tank or fill your prescription or do anything about that stack of bills that keeps you up at night . '' Her remarks in Ohio echo statements she made a day earlier in McAllen , Texas , when she said , `` I am in the solutions business . My opponent is in the promises business . '' Clinton was set later Thursday to hold events in Dayton and Columbus , Ohio . Obama was to be in his hometown of Chicago , Illinois , and had no public events scheduled . CNN contributor and Clinton supporter James Carville said the senator must do well in the March 4 Ohio and Texas primaries if she is to stop Obama 's momentum . Carville said he thought Clinton could still win the nomination . `` You know , this thing is close . Not all the Democrats have been heard from . ... If anybody can do this , I think she can , '' said Carville , a major force behind President Clinton 's successful 1992 campaign . Clinton 's aggressive stance may be in reaction to Obama 's momentum after he won eight contests in a row -- including victories by wide margins in Tuesday 's primaries in Maryland , Virginia and the District of Columbia . Watch how the so-called Potomac primaries put Obama on a roll '' In those contests , Obama also outpolled Clinton among demographic groups she had carried earlier -- women , lower-income voters and Latinos . Clinton is banking on those groups to carry her to victory in Texas and Ohio . The wins in the Potomac primaries gave Obama a lead over Clinton in the delegate count for the first time -- 1,253 to 1,211 , according to CNN calculations . `` In my neighborhood , you know , you had to win games if you wanted to brag , '' said Jamal Simmons , a Democratic strategist and Obama supporter . `` And I think right now , Barack Obama is ahead in delegates . He 's ahead in states . He 's ahead in the popular vote . He 's winning . `` Sen. Clinton has got to win some of these contests , you know , to get to the finals . '' Neither Clinton nor Obama is likely to pick up the 2,025 delegates needed to win the nomination outright before the primary season ends in June , mainly because Democrats divvy up each state 's delegates in proportion to the candidates ' share of the popular vote . Watch an outlook of the Democratic race '' The Democratic nomination likely will be decided by the roughly 800 superdelegates , which include party officers , elected officials and activists . Obama 's camp argues the superdelegates should support the candidate with the most popular support , as indicated by a majority of pledged delegates going into the convention . Clinton 's campaign , on the other hand , says the superdelegates should support the candidate they think will be the best nominee in the general election as well as the best president . Watch how the campaigns are fighting for superdelegates '' MoveOn.org , an influential liberal activist group , on Thursday said it would launch a petition drive calling on the superdelegates not to go against the popular vote . `` The worst thing for the party and democracy is if all these new voters feel like the nomination was brokered in a backroom somewhere . The superdelegates have got to let the voters decide , '' MoveOn.org Executive Director Eli Pariser said in a statement . MoveOn.org has endorsed Obama . In a possible indication that Clinton is going to fight for every delegate , her camp on Thursday announced that daughter Chelsea Clinton would be dispatched to Hawaii to campaign before the state 's primary Tuesday . Watch how each campaign is fighting for delegates '' However , Chelsea Clinton may face an uphill battle there since Hawaii is Obama 's native state . Bill Clinton on Thursday was scheduled to campaign in Wisconsin , which also holds its primary Tuesday . Recent polls in that state have shown a tight race between the two Democrats . A Strategic Vision survey conducted February 8 through Sunday finds Obama ahead of Clinton 45 percent to 41 percent , a lead outside the poll 's margin of error of 3 percentage points . Carville said Clinton could recover from a loss in Wisconsin . `` It certainly would be preferable for her to win Wisconsin , but I do n't put it in the same category as I would put Texas and Ohio on March 4 , '' he said . E-mail to a friend CNN 's Peter Hamby and Chris Welch contributed to this report .