LOUISVILLE, Ky. (WDRB) -- Indiana voters head to the polls on Tuesday, and for the first time in a long time, the eyes of the nation will be watching.

Heavy voter turnout is expected across Indiana, driven, primarily, by the Republican race for President.

For Ted Cruz, Indiana is almost do-or-die. If he wants to stop Donald Trump, Indiana and its 57 winner-take-all delegates is crucial. That's why Cruz has spent most of the past week in the state, including two rallies in Clark County.

"If Cruz wants any chance at all of creating a contested convention, he's going to have to win Indiana," said Joe Wert, political science professor at Indiana University Southeast.

He says it's unusual for Indiana to matter this late in the campaign.

"Generally by this time, even by usually mid-to-late March, in both parties, we pretty much know who's going to be the nominee," said Wert.

Though the GOP primary is getting most of the attention, there is also much at stake for Bernie Sanders in his showdown with Hillary Clinton for the Democratic nomination.

"If Sanders can come in to the convention with a fair amount of strength, he could have some influence over the party platform," said Wert.

The presidential primary is not all that could drive voters to the polls on Tuesday.

There is a hot five-way Republican battle for the 9th district congressional seat between businessman Trey Hollingsworth, State Senators Erin Houchin and Brent Waltz, Attorney General Greg Zoeller, and engineer Robert Hall.

Zoeller spent part of primary eve campaigning in Jeffersonville. He senses the surge in interest.

"Largest number of registrations that we've ever had in history," Zoeller said. "The absentee ballots and the early voting are largest in any election. We'll likely have a record number, which is good. We've always been historically low turnout in these primaries."

Four candidates are also going at it in the 9th District Democratic primary: Bob Kern, James McClure Jr., Bill Thomas, and Shelli Yoder. 

And two Indiana congressmen, Todd Young and Marlin Stutzman, are in a hotly contested race for the Republican U.S. Senate nomination

It's enough to satisfy even the most avid political junkie.

"They're going to come out in droves, I think," said Wert.

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