What's at stake in Monday's Iowa caucuses?

After months of speeches, millions of dollars, hundreds of promises and endless speculation, Iowa on Monday begins the actual voting. Iowans have correctly picked the Democratic nominee in every cycle since 1996 but missed the GOP mark the last two times around. Political viability and a shot at history are at stake for each of these candidates.

Rick Santorum: Former Pa. senator, R

He won Iowa's caucuses in 2012 but has little residual support, compliments of a field crowded with conservatives who don't seem like relics of the party's past. He spent the most time in Iowa, but it wasn't enough.

She earned some fans after strong showings in early debates. But sparring with Trump and saying she's Clinton's worst nightmare didn't translate into traction. Could she be VP or would that be too Sarah Palin?

Martin O'Malley: Former Md. governor, D

See that participation trophy up there? He's got that, and a higher profile after a probable early exit. Apparently Democratic voters don't really want a fresh face. You can bet he'll save the Iowa map for next time.

He was an Iowa winner, too — back in 2008 when fewer candidates pursued the evangelical vote. His sense of humor still wins him fans, but expect this minister to soon head back to the pulpit or to conservative TV.

This Jersey guy in the stubborn shadow of a bridge scandal never quite connected in farm country. His blunt talk and confidence are faring better among New Hampshire voters. His hope for fighting on lies in New England.

Remember when his swagger and cluelessness were going to doom him? Fuhgeddaboutit. Now the GOP's elite are whispering that he could win the nomination. But first, his fans must show up Monday.

The outrage champ has something in common with Trump (bear with us). His Iowa crowds are huge, passionate and filled with rookie voters. If they actually caucus and he wins New Hampshire, this could get interesting.

The soft-spoken doctor's improbable campaign made him the man of the moment — quite a few moments ago, before missteps on his life story. Diminished expectations mean a fourth-place Iowa finish would be a win.

The libertarian firebrand says he doesn't believe the polls, which is what candidates often say when they don't expect to do well. Fourth place would satisfy him, and he's counting on students to help him pull it off.

First and second in Iowa likely will go to Trump and Cruz. So the next finisher gets more than a third-place ribbon — it would vault him into contention in all the early states. An Iowa win would be a political earthquake.

Conventional wisdom says that only one governor will emerge with a real chance. His advantage is an earnest focus on competence. Oh, and no Republican has ever won the White House without carrying Ohio. Hmm.

His rivals are ganging up on him, a sure sign of worry. He's the outsider alternative to Trump, but recently was nudged out of first place. A win would be a game-changer, but second also would be a win. Any lower would not.