Barack Obama and Hillary Clinton face crucial tests in their gruelling White House fight today when voters in Indiana and North Carolina cast ballots in the latest Democratic showdowns.
The two states, with a combined 187 delegates to the August nominating convention at stake, are the biggest prizes remaining in the tight Democratic nominating race. After today, only six contests will be left.
"The stakes are high and the consequences are huge," Senator Clinton told supporters at a New Albany, Indiana, fire station last night, urging voters to think through their decisions.
US Democratic presidential candidate Hillary Clinton campaigns at a fire station in New Albany, Indiana
Polls close in Indiana at 7pm EDT (Midnight Irish time) and in North Carolina half an hour later, with results expected soon afterward.
Mrs Clinton has cut Mr Obama's advantage in North Carolina to single digits in most polls over the past few weeks. The two run closer in Indiana, where most polls show Mrs Clinton with a slight edge.
"Obviously we hope to do as well as we can, but, you know, we started out pretty far behind," she told reporters on her campaign plane last night. "I never feel confidant, I just try to do the best I can."
Mr Obama has an almost unassailable lead in pledged delegates who will help select the Democratic nominee to face Republican John McCain in November's presidential election.
If Mr Obama wins both contests today, it would end Mrs Clinton's slender hopes of overtaking him in either delegates or popular votes won in the state-by-state battle and spark a fresh flood of calls for Mrs Clinton to step aside.
Victories for Mrs Clinton in both states could fuel doubts about Mr Obama's electability and persuade some superdelegates - party insiders who are free to back any candidate at the nominating convention - to move toward her.