(CNN) -- 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 "doesn'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 don't put food on the table. Speeches don'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
What did Carville say? Who accuses Sen. Barack Obama of caving to special interests? Who doesn't need lectures on special interests? Who has challenged Obama's ability to deliver on his rhetoric? What did Clinton challenge? What did Clinton accuse Obama of? Who challenged Obama's ability to deliver on his rhetoric? Who says Obama "doesn't need lectures on special interests"?
said he thought Clinton could still win the nomination. the senator from New York Obama Clinton Obama's ability to deliver on his rhetoric. caving in to special interests. Clinton Bill Burton
question: What did Carville say?, answer: said he thought Clinton could still win the nomination. | question: Who accuses Sen. Barack Obama of caving to special interests?, answer: the senator from New York | question: Who doesn't need lectures on special interests?, answer: Obama | question: Who has challenged Obama's ability to deliver on his rhetoric?, answer: Clinton | question: What did Clinton challenge?, answer: Obama's ability to deliver on his rhetoric. | question: What did Clinton accuse Obama of?, answer: caving in to special interests. | question: Who challenged Obama's ability to deliver on his rhetoric?, answer: Clinton | question: Who says Obama "doesn't need lectures on special interests"?, answer: Bill Burton