"Shame on You, Barack Obama," 60-year-old Clinton, the New York Senator, said during a rally in Ohio, which is to hold the Democratic nominating contest on March 4 along with the southern state of Texas, charging the Obama campaign with producing misleading leaflets on her health care and free trade positions.

One of the Obama campaign mailings says that Clinton's health care plan would force Americans to buy coverage even if they could not afford it. The other says that Clinton "was not with Ohio when our jobs were on the line," describing her as a champion of the North American Free Trade Agreement (NAFTA) approved by her husband, former President Bill Clinton.

The former first lady suffered 11 straight losses to 46-year-old Obama since the Super Tuesday showdown of February 5 when two dozen contests took place, and is looking ahead to the strong showing in Ohio and Texas, the delegate-rich states that could determine the fate of her White House bid.