With 67 percent of ballots counted, the New York senator had 51 percent of the vote, compared to rival Barack Obama's 41 percent, Fox News reported.

Ohio, which was seen as a battleground state for the Democratic presidential nomination, has 141 delegates up for grabs Tuesday. Those delegates will be awarded to the candidates proportionally.

Political analysts said Clinton had to win the primaries in Ohio and Texas to remain a viable candidate.

To help Clinton win in Ohio, she has 20 campaign offices in the Buckeye State. Moreover, last week, former President Bill Clinton started an "88 hours, 88 counties to victory" campaign effort, RTT News reported.

Obama's camp, meanwhile, has 28 offices in the state, and the Illinois senator's campaign planned to knock on 1 million doors in Ohio to help bring out supporters.