The Republican and Democratic presidential primaries enter their third month on Tuesday, with dual contests in Wisconsin.
There are signals on both sides that the race could drag on until the last primary, which will be in California on June 7. And for Republicans, at least, the fight could go to the convention floor in July.
Two of the three remaining GOP candidates — Sen. Ted Cruz Texas and Gov. John Kasich of Ohio — have mathematically impossible odds of obtaining enough delegates before the convention.
Nevertheless, they are powering on, looking to stop frontrunner Donald Trump from clinching the nomination before the convention. Wisconsin could be a momentum-shifter: Cruz is favored to pull off a victory there.
Meanwhile, the upstart on the Democratic side, Sen. Bernie Sanders of Vermont, also stands as a slight favorite to upset former Secretary of State Hillary Clinton in the Badger State.
Our rankings are based on the Real Clear Politics averages of national polls and those in states voting in future contests (Wisconsin, New York, and Pennsylvania). We also factored in the candidates' delegate counts and their relative paths to the nomination, as well as their momentum (or lack thereof) over the past few weeks.
Since our most recent ranking, one more Republican candidate has dropped out of the race: Sen. Marco Rubio of Florida.
Here's a look at where all the candidates stand:
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5. John Kasich
Kasich picked up momentum last month with a win in his home state's primary.
But he has no chance to accumulate enough delegates to clinch the nomination before the convention, so he's banking that he can win a floor fight. Kasich's rivals are growing increasingly frustrated with his presence in the race — Trump said he would "automatically win" if Kasich dropped out of the race.
Those who talk up Kasich say he is a successful governor of a swing state with a record to point to and clear bipartisan appeal. He also has abundant experience from nearly two decades in Congress, including foreign-policy areas and his time as chair of the US House budget committee.
But that same bipartisan brand has hurt Kasich with the GOP base. He is to the left of most GOP candidates on immigration reform, and he expanded the federal Medicaid program under the Affordable Care Act — two issues that could doom him with hard-line conservatives.
National polling average among Republican voters: 20.6% (3rd)
Average in Wisconsin, New York, Pennsylvania polls: 20.3% (3rd)
Last month: 5
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4. Bernie Sanders
Sanders had perhaps the best single day of his campaign late last month, romping to landslide victories in Alaska, Hawaii, and Washington. He has won five of the past six Democratic contests.
Still, he faces challenging odds — he needs to win about 57% of the remaining pledged delegates to overtake Clinton in the delegate count.
Moving forward, the map doesn't look especially favorable: About 65% of the remaining delegates come from large states like California, New York, Pennsylvania, New Jersey, and Maryland.
National polling average among Democratic voters: 42.8% (2nd) Average in Wisconsin, New York, Pennsylvania polls: 39.3% (2nd)
Last month: 4
3. Ted Cruz
Cruz looks positioned to take down Trump in Wisconsin. After that, the map gets more challenging.
Late April is dominated by Northeast and mid-Atlantic contests more favorable to Trump — including delegate-rich New York, where polls have showed Trump above 50% in the state.
Cruz inspires a flood of enthusiasm among the GOP base, and he may be the best-positioned candidate from within the political sphere to back up the notion that he's not a typical politician, that he is the outsider the base wants despite his day job in Washington.
And his eye-popping fund-raising numbers mean he could be in the race for the long haul — perhaps all the way to the convention.
National polling average among Republican voters: 32.8% (2nd) Average in Wisconsin, New York, Pennsylvania polls: 27.1% (2nd)
Last month: 3
2. Donald Trump
Trump has lit the political world on fire since his entry into the race last summer, and he has showed surprising staying power. We're now on month No. 11 of "The Trump Show."
He has won a majority of contests so far, a feat unthinkable when he entered the race in June. And he appears poised to at least go into the convention with the most delegates of any Republican candidate.
There's a clear appetite among Republican primary voters for someone like Trump, who entered the race to controversy surrounding his position on illegal immigration. Business Insider discovered more of that when we followed him on the trail for a week last year.
National polling average among Republican voters: 40.4% (1st) Average in Wisconsin, New York, Pennsylvania polls: 41.9% (1st)
Last month: 2
1. Hillary Clinton
The delegate math is on Clinton's side going forward, even as she faces a potential loss in Wisconsin and a fight with Sanders in her adopted home state of New York.
The long-presumed Democratic nominee, Clinton has been a shakier-than-expected candidate. But she has a clear look at the nomination, and she would enter the general election with a slight advantage over Trump or Cruz.