The fate of Hillary Clinton's presidential bid rested with voters in Ohio and Texas on Tuesday, as they cast their ballots in her hard-fought Democratic duel with rival Barack Obama.
The New York senator, battling to snap Obama's string of 11 consecutive victories, needs wins in both big states to rejuvenate her struggling campaign and ensure the race moves on to Pennsylvania on April 22.
Losses in even one of the states could set off a stampede of party support for Obama, increase pressure on her to drop out and make it even tougher to cut Obama's lead in pledged delegates who choose the party nominee in November's presidential election.
Polls show the two Democrats in tight races in both Ohio and Texas. Rhode Island and Vermont vote on Tuesday as well.
"I think I know what's happening and I believe that we're going to do well tomorrow," Clinton told reporters in Ohio, dismissing suggestions of impending doom.
"Then we move on to Pennsylvania and the states still ahead. So I'm just getting warmed up."
Tuesday's contests also could put Republican front-runner John McCain, an Arizona senator, close to clinching his party's nomination. McCain is favoured to beat his last remaining major challenger, former Arkansas Gov. Mike Huckabee, in all four states.
Voting ends in Ohio at 7:30 p.m. EST (12:30 a.m. British time on Wednesday) and all voting in Texas will be over by 9 p.m. EST.
Clinton and Obama made last-minute appeals for votes in Ohio and Texas on Monday. Clinton rose before dawn to tour a car plant in Toledo, Ohio, and closed the day with a televised town hall meeting in Texas with time bought by her campaign.
She renewed her attacks on the Illinois senator over the North American Free Trade Agreement, an unpopular treaty in Ohio, which has suffered from manufacturing job losses.
Both candidates say the treaty should be renegotiated, but the Clinton campaign has highlighted reports an Obama adviser assured the Canadian government his opposition was political rhetoric and not substantive.
