New York's primary put an exclamation point on the front-runner status of both Hillary Clinton and Donald Trump. In any election cycle in recent history, their strong showings in different parts of the country and across demographic groups would have made them the presumptive nominees by now.

But this isn't just any election cycle. It is one where the front-runners are substantially weakened — Clinton by a relentless challenge from rival Bernie Sanders that has siphoned off much of the energy she had expected to tap as the first woman with a clear shot at the presidency. Trump, meanwhile, has become his party's bête noire, with a cadre of those loyal to his unique brand but intensely disliked by a significant portion of the electorate. These choices are the result of a curious hybrid of primaries, caucuses and Byzantine delegate selection that is on the verge of producing two of the most problematic candidates this nation has seen in some time.

So, what now? Establishment Democrats would like nothing better than for Sanders to bow out, his path to a first-ballot nomination now all but mathematically impossible. But there is no denying that Sanders' message on wealth inequality, the downsides of free trade, the need for labor protections, universal health care and affordable higher education has resonated deeply with many Americans — even if this page finds most of his proposals either impractical or unaffordable. He has proved to his party that even a senator from a small state can raise ample funds without kowtowing to PACs, corporations and megadonors. At 74, this career politician who has served in Congress since 1991 has become a hero to young voters, engaging their passions and loyalty in a way others will be studying for years.

For those reasons, Sanders should think carefully about the path forward. He may decide there is value in remaining in the race, despite lengthening odds. As recently as their last debate, he succeeded in pushing Clinton into embracing a $15 minimum wage. There may be other similar triumphs in coming weeks. But if he is to end on a grace note, Sanders should stick to issues and refrain from bruising personal attacks on the judgment and character of the candidate who is likely to be the party's standard-bearer. Fomenting division at this summer's convention would be ugly and could jeopardize the unity the nominee will need greatly come November.

Republicans face an entirely different dilemma. Their leading candidate breaks regularly with party doctrine — Trump recently denounced North Carolina's "bathroom bill" and said that on abortion he favors exceptions for rape, incest and the life of the mother. The more conservative Sen. Ted Cruz still lags well behind Trump, and in New York finished third to Gov. John Kasich of Ohio. At this point, Cruz and Kasich should stay in the race. Both can continue to test Trump in needed ways, if he is to be his party's nominee, and one of them may break through. For either man to withdraw now would almost certainly hand the nomination to Trump — unthinkable for many mainstream Republicans.