Republicans voting in Indiana's primary election on Tuesday might give New York billionaire Donald Trump an almost unstoppable advantage in his turbulent journey toward the party's presidential nomination.
The real estate mogul holds a double-digit polling lead in the Midwestern state over his main rival, US Senator Ted Cruz of Texas.
Fresh off a sweep of five Northeastern states last week, Trump wants a win in Indiana to put him within reach of the 1,237 delegates required to lock up the Republican nomination before the party's convention in July.
"If we win Indiana, it's over," Trump told a cheering crowd in Terre Haute, Indiana, on the eve of the vote.
Cruz has trumpeted Indiana, one of the last big states in the fight to get on the Nov. 8 presidential ballot, as his golden moment to stop Trump and force a brokered nomination at the convention.
He vowed on Monday to "compete to the end" but a loss in Indiana would be particularly crushing for the senator, who has argued that his brand of religious conservatism is a natural draw for heartland Republicans. He won the endorsement of conservative Indiana Governor Mike Pence.
Trump now has 996 delegates, compared with 565 for Cruz and 153 for Ohio Governor John Kasich, according to The Associated Press. Another 57 delegates are up for grabs in Indiana, a state that has voted Republican in nine of the last 10 presidential elections.
"I think we're going to have a great voter turnout and people are tired of what's happening with these politicians and they're just tired of seeing our country get ripped off," Trump told the "Fox & Friends" show on Tuesday.
Top Trump aide Corey Lewandowski told CNN on Tuesday the campaign expected to win more than required number of delegates - 1,300 to 1,400.
Trump has drawn both passionate support and vitriolic condemnation with his stands on immigration and national security - including a call to build a wall along the Mexican border that he says Mexico would pay for and a bid to temporarily ban Muslims from entering the United States.
Julie Blackwell Chase, a clerk treasurer in the town of Bedford in southern Indiana, said she voted early for Trump in part because she appreciated his willingness to break with conventional politics. "We need new blood," she said.
The outcome in Indiana may ride on the votes of evangelical Christians after Trump offered praise for Planned Parenthood family clinics and signaled support for gay and transgender rights - views that rankled some Christian conservatives.
Sam Shafer, 33, of Cloverdale, Indiana voted for Cruz on Tuesday, citing the Texas senator's strong respect for the constitution. Shafer is not a fan of Trump.
"There are no words," said Shafer, who owns a roofing company. "I don't care for him."
Cruz had hoped for smooth sailing in Indiana after he and Kasich reached a "stop-Trump" deal in which Kasich would steer clear of the state while Cruz would do likewise in Oregon and New Mexico.
Indiana has the second-largest delegate haul of the 10 states remaining in the 2016 Republican nominating contest, behind California, which holds its primary June 7.
On the Democratic side, front-runner Hillary Clinton holds a lead of more than 6 percentage points in Indiana over rival Bernie Sanders, according to an average of recent polls compiled by RealClearPolitics.
Despite Clinton's formidable delegate lead, the US senator from Vermont campaigned heavily in Indiana on his message against income inequality and Wall Street excesses.
Jeremy Williamson weathered cold rain in Indianapolis to vote for Sanders, who he thinks should stay in the race to push Clinton to be more progressive. "I want to see the political revolution that everybody's promising," he said.