The front-runners of both parties lost their respective primaries in Wisconsin Tuesday night — but the similarity ended there. Sen. Bernie Sanders easily beat Hillary Clinton, outperforming expectations that he might at best eke out a close win. But the math remains against him: There's almost no conceivable way for him to win enough delegates to take the Democratic nomination away from her. Sen. Ted Cruz's decisive win over Donald Trump (and Ohio Gov. John Kasich), on the other hand, made it more likely that the Republican primary fight will go all the way, culminating in a contested convention. 

The next big challenge for Trump and Clinton will be the April 19 primary in New York. As of now, both are leading. But the narrative that will emerge from Wisconsin could change that. 

RTSDL7W Republican presidential candidate Donald Trump speaks at a campaign event in Milwaukee, Wisconsin, United States, April 4, 2016. Photo: Reuters

Trump’s loss may pose a threat to his brand as a winner. Cruz (according to incomplete returns) took more than 50 percent of the vote in Wisconsin, a threshold that Trump has not crossed in any of his own wins. Cruz won won 69 percent of the vote in Utah.

The real-estate mogul came into Wisconsin after the roughest weeks of the campaign. In the days before the primary he was forced to walk back comments about punishing women who have abortions, and critical social media posts about Heidi Cruz: the first time he'd actually apologized for any of his controversial or inaccurate statements. So the media narrative and public perception going forward may focus for the first time not on his startling invulnerability to the usual laws of political physics, but his vulnerability — an important concern, since Trump has benefitted in a big way from an estimated $2 billion worth of free media time.

Trump would need to win more than 50 percent of the total delegates up for grabs in the remaining primaries to avoid a contested convention. Although some of the upcoming primaries may still be friendly ground for Trump, Cruz's Wisconsin win was also a victory for the increasingly energized #NotTrump forces. The Texas senator had argued throughout the early primary season that when and if he got to battle Trump one-on-one, he would win. Gov. Kasich remains in the race — to the Cruz camp's frustration — but it is essentially a two-person race now, and the NotTrump movement is likely to help Cruz narrow the pledged delegate gap. He told supporters in his Tuesday victory speech that he could garner the needed 1,237 delegates but experts consider that virtually impossible.   

RTSDLAH Democratic U.S. presidential candidate Bernie Sanders speaks at a campaign rally in Milwaukee, April 4, 2016. Photo: Reuters

The situation on the Democratic side is different. Even with a better-than-expected performance in Wisconsin that is his sixth win in a row, Sanders has a slim path forward if he hopes to claim the Democratic nomination. He has momentum. But Clinton leads him among pledged delegates 1,271 to 1,024. Sanders’ win in Wisconsin may move him 10 delegates closer to the former secretary of state, but that's not mathematically significant. 

In New York, a state with 247 delegates up for grabs, Sanders trails Clinton by 11 percent of the vote with 42.5 percent support in averages of polls compiled by Real Clear Politics. Clinton’s formidable campaign infrastructure, with deep roots in the state, will turn out every possible vote. 

New York is Trump's home state as well. But his campaign team appears in disarray; it has never been strong on traditional ground-game politics; and the candidate himself has misplaced his previous, almost preternatural sense of what he can and can't say.  When he ran against 16 other Republican candidates, he was a winner. With the battle now Trump against #NotTrump, the odds have shifted.