The Republican and Democratic presidential primaries are heading into the home stretch of some of the lengthiest battles in both parties' recent histories.
There are signals on both sides that the race could drag on until the final primary day of June 7, when California votes. And for Republicans, at least, the fight could go to the convention floor in July.
Five candidates officially remain in the race — though only two have mathematically realistic chances of claiming their parties' respective nominations before their conventions.
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.
On the Democratic side, Sen. Bernie Sanders needs a seemingly improbable turn of events, given Democratic primary rules that give more of an edge to the frontrunner at this point.
Nevertheless, they are all powering on, looking to stop frontrunners Donald Trump and Hillary Clinton.
Our rankings are based on the Real Clear Politics averages of national polls and those in states voting in upcoming contests (Pennsylvania, Maryland, Connecticut, and Indiana). 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.
See where the candidates stand in the rankings:
April 26 Presidential Power Rankings (BI)
POWER RANKINGS: Here's who has the best chance at being our next president
5. John Kasich, Republican, Ohio governor
Kasich picked up momentum last month with a win in his home state's primary.
But the road before, and since, has been virtually empty for the Ohio governor. 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.
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: 22.3% (3rd)
Average in Pennsylvania, Maryland, Connecticut, and Indiana polls: 23.9% (3rd)
Last month: 5
(Photo via REUTERS/Carlos Barria)
4. Bernie Sanders, Democrat, senator from Vermont
Sanders had perhaps the best single day of his campaign late last month, romping to landslide victories in Alaska, Hawaii, and Washington. But he got tripped up in New York, with a bigger-than-expected loss to Clinton in her adopted home state.
And he faces challenging odds — he needs to win about 71% of the remaining pledged delegates to overtake Clinton in the pledged-delegate count, according to NBC.
Moving forward, the map doesn't look especially favorable. In a system in which delegates are allocated proportionally, it will be hard for him to make up real ground in large states like California, Pennsylvania, New Jersey, and Maryland.
National polling average among Democratic voters: 46% (2nd) Average in Pennsylvania, Maryland, Connecticut, and Indiana polls: 40% (2nd)
Last month: 4
(Photo by Scott Eisen/Getty Images)
3. Ted Cruz, Republican, senator from Texas
Cruz always had favorable ground in Wisconsin. After that, the map was supposed to get more challenging — and it has.
Late April has overwhelmingly featured Northeast and mid-Atlantic contests more favorable to Trump — including delegate-rich New York, which Trump won with more than 60% of the vote. With more states from the regions on the map to come, Indiana's May 3 primary is looking more and more like a must-win for the Texas senator.
Still, 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.
National polling average among Republican voters: 30.3% (2nd) Average in Pennsylvania, Maryland, Connecticut, and Indiana polls: 24.7% (2nd)
Last month: 3
(Photo via REUTERS/Aaron P. Bernstein)
2. Donald Trump, Republican, businessman
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. He appears poised to at least enter the convention with the most delegates of any Republican candidate — and after a gigantic win in New York, he seems better positioned to capture the nomination heading into the convention.
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: 42.3% (1st) Average in Pennsylvania, Maryland, Connecticut, and Indiana polls: 44.6% (3rd)
Last month: 2
(Photo via REUTERS/Eduardo Munoz)
1. Hillary Clinton, Democrat, former secretary of state
The delegate math is on Clinton's side going forward, especially now that she has avoided her biggest potential pitfall in the New York primary.
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.
"I'm not going to be responding to him," Clinton said in a recent interview with Business Insider. "I have pretty thick skin. I've been in the arena a long time, and that means that I am not going to get down with him and go insult for insult."