Donald Trump
Donald Trump Reuters

Donald Trump holds a 15-point lead over Ted Cruz in the May 3 presidential primary race in Indiana, an NBC News/Wall Street Journal/Marist poll released on Sunday found.

Trump gets support from 49 percent of likely Republican primary voters — followed by Cruz at 34 percent and John Kasich at 13 percent, the poll found.

If that margin in Indiana holds on Tuesday, Trump would be on a glide path towards obtaining the 1,237 delegates he needs to win the Republican nomination on a first ballot at the GOP convention in July.

On the Democratic side, Hillary Clinton leads Bernie Sanders by just four points, 50 percent to 46 percent.

"In Indiana, Trump is positioned to corral all the [state's 57] delegates, which will be a big prize toward winning the nomination outright," Lee Miringoff, director of the Marist College Institute for Public Opinion, said. "Clinton and Sanders are more likely to divide the delegate pool, which will do little to change the narrative on the Democratic side."

The poll was conducted between April 26 and 28, mostly after Trump's six-consecutive primary victories in Northeast and Mid-Atlantic states, as well as after Cruz and Kasich announced an alliance, whereby Kasich wouldn't campaign in Indiana to help Cruz, in exchange for Cruz not campaigning in Oregon and New Mexico.

The poll found that 58 percent of likely Republican primary voters in Indiana say they disapprove of Cruz and Kasich teaming up to beat Trump, while 34 percent say they approve of the move.

Trump himself blasted the alliance after it was announced last week, saying, “It is sad that two grown politicians have to collude against one person who has only been a politician for ten months in order to try and stop that person from getting the Republican nomination.”