Republican front-runner Donald Trump on Thursday talked up "New York values" and urged his home state voters to give him a big win next week, but his rivals warned nominating Trump could lead to disastrous losses to the Democrats in the Nov. 8 election.

The New York billionaire is in danger of being forced to try to capture the Republican presidential nomination through a contested convention because opposition from rivals Ted Cruz and John Kasich is chipping away at his lead.

As protesters chanted outside and waved signs against Trump, Trump told the New York state Republican Party's gala that he needs the momentum that a victory in the state's primary would bring next Tuesday.

Whether Trump can win the 1,237 delegates he needs for the nomination is an open question as both Cruz, a U.S. senator from Texas, and Ohio Governor Kasich, try to block him from getting enough delegates. They want to extend the fight to a contested convention in Cleveland when Republicans gather to formally choose their nominee in July.

Trump has drawn many protests for policy positions that include building a wall along the U.S. border with Mexico, deporting 11 million illegal immigrants and banning Muslims temporarily from entering the United States. "We risk losing everything from the White House to the courthouse to the state house if we don't advance a positive, uplifting, unifying message to this country. That is what we need to do," said Kasich, who spoke after Trump.

Before the event started in the Grand Hyatt hotel near Grand Central Station, a group of protesters stormed the hotel mezzanine with a banner that read: "NYC Rejects the Party of Hate." Eleven of them were reported arrested. Outside the hotel, many anti-Trump demonstrators called the New York billionaire businessman a fascist or white supremacist. They even teased him about his signature hairdo. "We Shall Over Comb," read one sign. Others said: "Deport Trump," "No allegiance for Trump," and "Black lives matter."