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Milwaukee (CNN) Ted Cruz's win over Donald Trump in Wisconsin means a contested GOP convention is not only possible, but may be probable. And Bernie Sanders reminded Hillary Clinton that the Democratic race isn't over yet.

Wisconsin was a must-win for both Cruz and Sanders as the 2016 race shifts to New York , where both front-runners will try to regain their footing in the state they call home. Both did just that -- and they racked up big margins of victory, with Cruz besting Trump by 15 percentage points and Sanders ahead of Clinton by 13 points.

Here are five takeaways from Tuesday's contests:

A contested convention is more likely

For Trump, getting the delegate math to add up to 1,237 before the Republican National Convention in Cleveland was always a tall task.

Photos: Who's running for president? Photos: Who's running for president? Ted Cruz, Donald Trump, John Kasich, Hillary Clinton and Bernie Sanders, Hide Caption 1 of 6 Photos: Who's running for president?



"So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Businessman Donald Trump announced June 16 at his Trump Tower in New York City that he is seeking the Republican presidential nomination. This ends more than two decades of flirting with the idea of running for the White House."So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Hide Caption 2 of 6 Photos: Who's running for president?



"These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Sen. Ted Cruz of Texas has made a name for himself in the Senate, solidifying his brand as a conservative firebrand willing to take on the GOP's establishment. He announced he was seeking the Republican presidential nomination in a speech on March 23."These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Hide Caption 3 of 6 Photos: Who's running for president? Ohio Gov. John Kasich joined the Republican field July 21 as he formally announced his White House bid.



"I am here to ask you for your prayers, for your support ... because I have decided to run for president of the United States," Kasich told his kickoff rally at the Ohio State University. Hide Caption 4 of 6 Photos: Who's running for president?



"Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hillary Clinton launched her presidential bid on April 12 through a video message on social media. The former first lady, senator and secretary of state is considered the front-runner among possible Democratic candidates."Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hide Caption 5 of 6 Photos: Who's running for president?



"This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Sen. Bernie Sanders , an independent from Vermont who caucuses with Democrats, announced his run in an email to supporters on April 30. He has said the United States needs a "political revolution" of working-class Americans to take back control of the government from billionaires."This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Hide Caption 6 of 6

It just got much more difficult.

Cruz's big Wisconsin win raises the possibility that Trump romps in the Northeast, wins California and still comes up just short, throwing the nominating battle into a contested convention.

Cruz tried again to consolidate the anti-Trump movement , touting in a Milwaukee speech the $2 million he said his campaign has raised Tuesday alone.

JUST WATCHED What is a brokered convention? Replay More Videos ... MUST WATCH What is a brokered convention? 01:35

He also made a play to unify Republicans, dropping his usual attacks on Trump and instead taking aim at Clinton in his victory speech.

"Either before Cleveland or at the convention in Cleveland, together, we will win a majority of the delegates, and together, we will beat Hillary Clinton in November," Cruz said.

The Texas senator's supporters -- and Republicans allied with anybody whose name isn't Trump -- crowed that Wisconsin marked a turning point in the race, especially as Trump watches delegates slip away in states he's already won because his campaign hasn't mastered the contest's procedural intricacies.

"GOP voters in Wisconsin rejected Donald Trump just like the entire Republican base will do in Cleveland this summer," Katie Packer, a Republican strategist who helms the anti-Trump Our Principles PAC, said in a statement.

Trump has to regroup

The good news for Trump: The next stop is New York, where the billionaire calls home and is up in the polls.

But Wisconsin shows he has some brand maintenance to do.

Coming off perhaps the worst week of his campaign , Trump -- who'd claimed as recently as Tuesday morning that he thought he'd win the Badger State -- fell far short. He split the vote with Cruz of Republicans who said they wanted a candidate who could bring change. He was blown away by those worried about electability.

One especially concerning figure for Trump: He was blown out by 22 percentage points by Cruz in suburban areas and 13 points in urban areas, compared to just 3 points in rural areas. That's bad news as the race moves to the densely-populated east coast.

That all explains why Trump lost, and lays out the challenges he confronts: Now he has to face down adversity and appear, in his own words, "more presidential."

The only silver lining might have been that there was no significant gender gap -- an indication Trump's two stumbles and subsequent reversals over abortion didn't depress his support from women.

Bern-ing hot headed into New York

Sanders got an affirmation of his momentum, with six wins in the last seven contests. He will need that momentum to stay strong if he's going to truly knock Clinton off her heels

To keep his streak going, Sanders will need to beat her out east -- in New York on April 19, and then in some combination of Pennsylvania, Maryland, Connecticut, Rhode Island and Delaware the following week.

In those states, Sanders will be competing without his typical advantages. In Wisconsin, loyal Democrats split 50-50, but Sanders won independents 71-29. The east coast races, though, are closed contests -- which means only registered Democrats can participate, limiting his ability to bring new, young voters into the process.

What Wisconsin gives Sanders is the ability to keep raising big dollars, and keep his supporters energized in states where organizational work will be especially important. He has outraised Clinton, $109 million to $75 million, in the last three months.

Before heading east, Sanders made a stop in Laramie, Wyoming, where he'll try to make it seven out of eight states when that state holds its caucuses Saturday.

"I was told that about 5,000 people participated in the last Wyoming caucus. It looks like all of them are here tonight," he joked as he started his speech, leaning hard into one buzzword: "Momentum."

"I know a little bit about New York because I spent the first 18 years of my life in Brooklyn, New York. Now please keep this a secret -- do not tell Secretary Clinton; she's getting a little nervous and I don't want her to get more nervous -- but I believe we've got an excellent chance to win New York and a lot of delegates in that state," he said.

Clinton waiting for Sanders

Wisconsin was the kind of state -- overwhelmingly white, and independents are allowed into party primaries -- that Sanders had to win. And he did: He crushed Clinton among voters 18-29 by his standard margin of 82% to 18%, and won those 30-44, two to one. He won white voters, 59% to 41%. That number was flipped among non-whites, but in Wisconsin, 83% of the Democratic electorate was white.

States like New York that are far more diverse have proven to be Clinton country. And the former secretary of state is wasting no time welcoming Sanders back to the state where he grew up.

JUST WATCHED Bernie Sanders feeling media heat after new interview Replay More Videos ... MUST WATCH Bernie Sanders feeling media heat after new interview 01:23

Readers of The New York Daily News will see a front-page story Wednesday denouncing "Bernie's Sandy Hook shame." Sanders Tuesday faced blistering criticism over his interview with the newspaper's editorial board , where he seemed unable to go beyond top-level talking points on his core policy issues, like breaking up the big banks.

In an unusual move, Clinton's campaign sent out the entire Sanders transcript as part of a fundraising email.

"We've said for a long time that this primary is about who's really going to be able to get things done. And from reading this interview, you get the impression Senator Sanders hasn't thought very much about that. In fact, even on his signature issue of breaking up the banks, he's unable to answer basic questions about how he'd go about doing it, and even seems uncertain whether a president does or doesn't already have that authority under existing law," Clinton aide Christina Reynolds wrote.

The GOP's battleground woes

If Gov. Scott Walker's experience of three statewide wins in four years shows anything, it's that Republicans can win in Wisconsin.

But Cruz and Trump may have an uphill climb in November.

Exit polls showed that only 62% of Republicans said they'd vote for Trump in the fall. Another 10% said if he's the nominee, they'd support Clinton, while 17% said they'd back a third-party candidate and 8% said they wouldn't vote at all.

For Cruz, the numbers were similar: 66% said they'd vote for him, while 6% said they'd back Clinton. But 18% said they'd pick a third-party candidate, and another 6% would stay home.

It's an ominous sign for the fall. Wisconsin isn't a must-win state for a Republican in the general election -- but it is winnable, and, like Illinois, Pennsylvania and New Hampshire, it's home to a vulnerable senator (Ron Johnson) who the GOP hopes will be part of a governing majority next year.

Those exit poll numbers are, in theory, good for John Kasich , because they bolster his argument that he's the only electable Republican left standing.

But the Ohio governor has his own problems. The same factors that hurt Trump -- Wisconsin is highly educated and less angry -- should have helped Kasich. Yet he finished a distant third, once again failing to lend any credibility to his case for staying in the race.