Donald Trump said Tuesday that he would no longer honor his pledge to support the eventual Republican nominee for president, while fellow candidates Ted Cruz and John Kasich refused to say whether they would back the party's pick.

All three GOP contenders appeared at a CNN town hall in Milwaukee one week before Wisconsin's April 5 primary.

When asked if he would keep the pledge he signed last September, Trump responded "No, I won't." The real estate mogul explained that he was taking back the pledge because, "I have been treated very unfairly," and listed the Republican National Committee and party establishment among those he believes have wronged him.

Cruz, who is running second to Trump in the delegate race, shrugged off the question of whether he would support Trump in November, saying "Donald is not going to be the GOP nominee. We're going to beat him." The Texas senator added that nominating Trump "would be an absolute train wreck" and "would hand the general election to Hillary Clinton."

Trump, who followed Cruz on the town hall stage, said he didn't need a promise of support from Cruz.