Democratic US presidential candidates Barack Obama and Hillary Clinton faced critical tests in their White House race today, as millions of voters in Indiana and North Carolina cast ballots.
The two states, with a combined 187 delegates to the August nominating convention at stake, are the biggest prizes left in the race to pick the party's presidential candidate in November's election. After today, only six contests remain.
Obama and Clinton appear headed to a split of the two states. Obama leads opinion polls in North Carolina and Clinton is favored in Indiana.
"I think it's going to be close. I don't think anybody really knows exactly what's going to happen," Obama told reporters in Greenwood, Indiana.
A pair of losses would be disastrous for Clinton, the New York senator and former first lady who is struggling to overtake Obama in the White House race.
She has cut Obama's advantage in North Carolina to single digits in most polls over the past few weeks. The two run close in polls in Indiana, where Clinton has a slight edge.
"Every race is filled with the unexpected. It's like life. You never know what's going to happen," Clinton said during a visit to the Indianapolis speedway.
Her campaign chairman, Terry McAuliffe, predicted on MSNBC that Clinton would win Indiana. "And I think we're closing very fast in North Carolina," he said.
Polls in both states were scheduled to close in Indiana at 7pm EDT (2300 GMT) and in North Carolina at 7:30 pm EDT (2330 GMT), with results expected soon afterward.
If Obama wins in both Indiana and North Carolina, it would end Clinton's slender hopes of catching him in either delegates or popular votes won in the nomination battle and spark renewed calls for her to step aside.
Clinton victories in both states could fuel doubts about Obama's electability and persuade some superdelegates - party insiders free to back any candidate at the nominating convention - to move toward her.
Neither can win enough delegates to clinch the race before voting ends on June 3, leaving the decision to the nearly 800 superdelegates.
A split decision leaves the race largely unchanged before the last six contests, with 217 delegates at stake.