Your guide to today's Indiana primary

Republican presidential candidate Donald Trump greets former Indiana basketball coach Bob Knight during an April 27 campaign stop in Indianapolis. (AP Photo/Darron Cummings)

Republican presidential candidate Donald Trump greets former Indiana basketball coach Bob Knight during an April 27 campaign stop in Indianapolis. (AP Photo/Darron Cummings)

The Hoosier State is the only one voting today, and it could be pivotal for Democrats and Republicans.

The challengers are sure to fight on, and no one will mathematically clinch today, but we could look back on Indiana as the final nail in the coffin for Ted Cruz and Bernie Sanders.

Republicans (57 delegates):

While Cruz drew chuckles for calling a hoop a "basketball ring," Donald Trump has brought in a slew of the state's big sports names to his side in recent days. Former Indiana basketball coach Bobby Knight used salty language to declare Trump could have played for him, while former Notre Dame football coach Lou Holtz praised Trump's "first class" hotels and golf courses and predicted the same for the United States.

Cruz's half-hearted endorsement from Gov. Mike Pence just does not have the same oomph.

This was supposed to be the Texan's moment to make sure Trump does not have 1,237 delegates before the festivities get under way in Cleveland. John Kasich backed off to encourage #NeverTrump-ers to get behind Cruz in the state with a sizable evangelical population.

But polls are showing Trump safely ahead, and there's more to it than love for an irascible chair-thrower. The Rust Belt manufacturing base that helped carry the billionaire in neighboring Illinois is only magnified here, and his Northeastern sweep was a momentum boost.

The statewide winner gets 30 delegates, with the rest going to the winner of each congressional district -- no second place consolation prizes. This, too, does not bode well for Cruz, whose support appears to be bunched around Indianapolis.

Democrats (92 delegates):

Hillary Clinton is talking about the general election, while Sanders has all been ruled out and is talking about contesting the convention. It is almost reminiscent of the scenario before the March 8 Michigan primary, when Sanders' stunning win propelled him forward and forced the nomination into a longer slog than anticipated.

In this case, polls show Sanders closer to Clinton than they did in Michigan, so another Rust Belt upset is possible. But Clinton continues to control the delegate math, and Sanders' team is making increasingly tortured arguments about why superdelegates should switch their support to the guy who is behind and who has made his campaign all about spurning such insiders.

Democrats' proportional system means a narrow Indiana win won't do much to change delegate math, but with the media attention on the only state voting today, it can perhaps get Sanders some more money and a second look from wavering voters in the last few states.

A Clinton win, meanwhile, will amplify talk about which speaking slot Sanders gets in Clinton's Philadelphia coronation.

Polls: Gravis (April 28-29): Trump 44, Cruz 27, Kasich 9. NBC/WSJ/Marist (April 26-28): Trump 49, Cruz 34, Kasich 13; Clinton 50, Sanders 46. CBS/YouGov (April 20-22): Trump 40, Cruz 35, Kasich 20; Clinton 49, Sanders 44. Fox News (April 18-21): Trump 41, Cruz 33, Kasich 16; Clinton 46, Sanders 42.

Candidate Visits: Trump was in Evansville on Thursday; Terre Haute and Fort Wayne on Sunday; and Carmel and South Bend on Monday. Cruz has practically lived in Indiana in recent weeks -- from Friday through today he was scheduled to hit Indianapolis, Jeffersonville, Evansville, Lafayette, Marion, Bloomington, Osceola, Westfield and Evansville again.

Clinton was in Indianapolis on Sunday. Sanders was in South Bend on Sunday; and Evansville, Fort Wayne and Indianapolis on Monday.

Links: Last minute negative in Indiana, as Cruz ad says Trump is 'Lying' (Politico)

The delegate picture looks really good for Trump in Indiana -- statewide and at the district level (FiveThirtyEight)

Pence joined Cruz in his final day on the Indiana campaign trail, while Trump downplayed the endorsement (Indianapolis Star)

Sanders needs an Indiana win to reverse momentum (New York Times) The challengers are sure to fight on, and no one will mathematically clinch today, but we could look back on Indiana as the final nail in the coffin for Ted Cruz and Bernie Sanders.