The Battle of New York: Why This Primary Matters

It's primary day in New York and front-runners Hillary Clinton and Donald Trump are leading in the polls.

Trump is now vowing to win enough delegates to clinch the Republican nomination and prevent a contested convention. But Sens.Ted Cruz, R-Texas, Bernie Sanders, D-Vt., and Ohio Gov. John Kasich and aren't giving up just yet.

A big win in New York could tip the scales for both the Republican and Democratic front-runners in this year's race for the White House. Clinton and Trump have each suffered losses in recent contests, shifting the momentum to their rivals.

"We have won eight out of the last nine caucuses and primaries! Cheer!" Sanders recently told supporters.

While wins in New York for Trump and Clinton are expected, the margins of those victories are also important.

Trump needs to capture more than 50 percent of the vote statewide if he wants to be positioned to win all of the state's 95 GOP delegates. That would put him one step closer to avoiding a contested convention.

"We've got to vote and you know Cruz is way, way down in the polls," Trump urged supporters.

Meanwhile, Sanders is hoping for a close race in the Empire State. A loss by 10 points means he'll need to win 80 percent of the remaining delegates to clinch the nomination.

Despite a predicted loss in New York, Cruz hasn't lost momentum. He's hoping to sweep up more delegates this weekend while he's talking about how he can win in November.

"Because if I'm the nominee, we win the General Election," Cruz promised his supporters. "We're beating Hillary in the key swing states, we're beating Hillary with Independents, we're beating Hillary with young people."

For now, Cruz, Kasich, and Sanders have all moved on from New York to other states. Trump and Clinton are the only two staying in their home state to watch the results come in.