All eyes are on Tuesday's primaries in five states, especially Florida and Ohio, for the clearest clues yet as to whether GOP front-runner Donald Trump can ride his momentum to the 1,237 delegates he'll need to secure the nomination.
Tuesday's primaries are important not only because two of them are happening in candidates' home states, but also because it's the first day that states can allocate their delegates on a winner-take-all basis--meaning whoever wins certain states going forward will get a much bigger delegate prize out of it.
What's at stake on Tuesday for each of the candidates, and what do their paths look like after the votes come in Tuesday night? Here's a guide from CBS News:
The stakes on Tuesday
Political operatives are anticipating three distinct possible outcomes on Tuesday:
First off, Trump could sweep Ohio and Florida, giving him big delegate victories and likely meaning he'll do well in the other states on the map that day (North Carolina, Illinois, Missouri). Though he'd still be far from the magic 1,237 number, winning those states could give the GOP front-runner the momentum he needs to start winning by bigger margins going forward and ultimately wrap up the nomination.
"Looking at those percentages, it's very difficult for someone other than Trump to get to 1,237 before the end of this," said Josh Putnam, a University of Georgia professor who tracks delegate math on his website, Frontloading HQ. "The question is whether it's likely for Trump to held back from 1,237 or gets there."
The second and third possibilities are that Trump loses either Ohio or Florida, or loses both those states. In either of those scenarios, the results could provide a serious opening for Trump's opponents to both pick up larger numbers of delegates and help shift the narrative away from one of the front-runner's strength and inevitability.
Right now, Kasich either leads or ties Trump in Ohio; a CBS News Battleground Tracker poll out Sunday found the two men in a dead heat at 33 percent each. Florida polling, on the other hand, gives Trump a double-digit lead: the CBS Battleground poll out of Florida put him at 44 percent, compared with 24 percent for Cruz and 21 percent for Rubio.
Anti-Trump operatives maintain that even if Trump does sweep on Tuesday, it will be no easy matter for him to get to 1,237 before the convention. Trump has won about 44 percent of all the delegates that have been awarded so far--and in order to reach 1,237, he'd need to start winning more than half in the states that have yet to vote. (At this point in 2012, for example, Mitt Romney had won 56 percent of the delegates awarded by this point in the race.)
"Trump can win ALL the delegates in the Virgin Islands, Delaware, Oregon and New Jersey... AND win the large majority of delegates in Missouri, New York, Pennsylvania, Indiana and California, AND win DC, North Carolina, Wisconsin, Connecticut, Maryland, West Virginia, Washington and New Mexico and STILL FALL SHORT of the 1,237 threshold," says a memo from Our Principles PAC, the main anti-Trump group.
Ultimately, losing Florida, Ohio or both also signals Trump will have problems in other states across the map on Tuesday -- and would show at least the beginnings of a shift in the way people view him. After a weekend of headlines featuring the violence and chaos at his recent rallies, it's tough to say how voters will react, though his voters to this point have shown themselves to be "remarkably durable over this campaign in all previous states," in the face of all the criticism he's faced, CBS News' Battleground Tracker poll pointed out Sunday.
"If Trump loses both Florida and Ohio, then he's probably going to lose two of the other three -- because something will have happened to have diminished his support, or maybe voters have walked to the precipice, looked over and decided to move back," said Larry Sabato, director of the Center for Politics at the University of Virginia. "At which point it's hard to see how you wouldn't have a contested convention."
If you're Kasich, Cruz or Rubio, Putnam said, the rest of the primary season "just becomes a matter of peeling off as many delegates as you can here and there, and then playing to your strong suit where it happens on the map."
So where would that be? Each of the three remaining non-Trump candidates has different geographic strengths and weaknesses, and for each of them the race will be on -- not to 1,237, necessarily, but just to amass as many non-Trump delegates as possible.
Even experienced political operatives say it's tough to think too far beyond Tuesday, just given how much the field could change based on the results. If Rubio loses Florida, for example, it's hart to imagine a path forward for him in the race. If Kasich loses Ohio, the same is true for his candidacy. Either candidate's exit from the race could mean a very different landscape for the rest of the primary season, and it can't be taken for granted that their supporters gravitate to another non-Trump choice.
"A lot of it, I think, in that scenario depends on what happens with the non-Trump voters as he moves through the other states," said Republican strategist Terry Nelson. "Are they going to consolidate against Trump and support the remaining candidates, or are some of them going to go vote for Trump?"
Kasich's argument hinges on his being able to win more moderate-to-blue states down the line, especially a handful of those that vote on April 26. In various interviews, including one with CBS News' Major Garrett, he referenced Pennsylvania, Connecticut and New Jersey as explicit down-the-calendar opportunities for him.
The reality, though, is that thus far Kasich has amassed just 52 delegates -- and even if he won Ohio and all those states he mentioned and took most or all of their delegates, he'd barely break the 300-delegate mark. That number is far from what he'd need to win the nomination, to be sure, and is only a fraction of the delegates it will take to collectively stop Trump.
Cruz's path is murky as well, though his strategy is becoming clearer: focusing on more under-the-radar states so he can pick up delegates and some statewide victories along the way. Lately, for example, he's largely left Florida and Ohio alone in favor of spending his time in Missouri instead--a state with 52 delegates, which is no small prize.
Much of what comes later on the map doesn't really play to Cruz's strengths: thus far he's tended to do best in smaller caucus states, as well as some places across the South where he focused many of his resources. After Tuesday, there are no remaining GOP states on the map that hold caucuses; Cruz may look to places across the Mountain West and the Great Plains like Utah on March 22, Nebraska on May 10 and South Dakota and Montana on June 7 to find victories further down the calendar.
With 356 delegates thus far, according to CBS News calculations, Cruz is by far the closest competitor to Trump--he even noted in last week's Republican debate in Miami that he and Trump are the only candidates remaining with a mathematical shot at winning the nomination. But many of the places Cruz could expect to do well going forward are smaller states with fewer delegates, meaning that outcome is unlikely for him.
The states Cruz could be strong in "are not delegate-rich states," Putnam said. "Three of them are winner-take-all, but --mmaybe he pushes 500, which is good enough for second in the delegate count but that's only consequential if Rubio and Kasich can pull some weight."
Rubio's way forward is also somewhat unclear: his focus has singularly been on Florida recently, with no hint of the states he'll target once his home state has voted. Given how much he and Kasich seem to have been competing for the same voters -- enough so that Rubio encouraged his backers to support Kasich in Ohio in the hopes of stopping Trump -- it's likely they would continue competing for many of the same states. If the senator wins his home state, then he'll likely look to the bluer, more urban East Coast states that Kasich has his eye on as well.
Ultimately, Tuesday will provide a huge amount of insight into which of these possibilities could be on the table going forward. Regardless, operatives note it could still be a long time before Trump or any other candidate crosses that 1,237 mark.
"There's a perception that even when all of this kind of winnows down that it's done, and it is done from a contested standpoint," Nelson said. "But from a mechanical standpoint, it still takes a while."