But if the Indiana surveys hold true, Trump will notch his seventh victory in a row and roll within reach of the delegates he needs to clinch the nomination — and possibly avert a messy, contested convention.

The polls have been wrong before in the volatile Republican presidential contest, especially in Iowa, where Trump wound up losing to Cruz in a surprise result.

WASHINGTON — Donald Trump’s once improbable campaign may be on the verge of taking him all the way to the Republican nomination, as polls show him poised to deliver a crushing blow in Indiana on Tuesday to his strongest remaining rival, Ted Cruz.


“If we win in Indiana, it’s over,” Trump said Monday during a rally in Indiana. Of his rivals, he added, “They’re finished. They’re gone. They’re gone. They have no path. Whereas, I have a very easy path.”

A CNN poll released Monday found that 91 percent of Republicans across the country believe that Trump will be their party’s nominee. But some 49 percent of those surveyed said the party will not unite after the bloody civil war over Trump’s aggressive and controversial campaign.

Even while Trump has expanded his vote totals and made inroads in winning over members of the GOP elite, his problems with party officials and delegate rules continued Monday. In New Hampshire, state GOP officials attempted to fill eight convention committee slots with non-Trump delegates, even though Trump won the state decisively.

On the Democratic side of Indiana’s vote Tuesday, Hillary Clinton held a small lead in polls and was in line to edge another step toward clinching the nomination, despite continued protestations from Bernie Sanders. Clinton also announced a large fund-raising haul for the month of April, for the first time this year surpassing Sanders in their monthly totals.

Cruz, who has said Indiana is crucial for his campaign, has blitzed the state over the last week. But in a bit of bad luck that produced a widely aired video clip, Carly Fiorina, his would-be vice president, fell off a stage after introducing Cruz and his wife. (She was uninjured during the Sunday spill.)


Cruz later confronted Trump supporters in a testy exchange during a stop at a restaurant. “Do the math!” one yelled at him, alluding to him having no shot at winning the nomination outright. “Are you Canadian?” another asked. As Cruz attempted to explain shifts Trump has made on immigration, a man repeatedly shouted, “Lyin’ Ted!”

“Donald Trump is deceiving you,” Cruz told the man. “He is playing you for a chump.”

Cruz vowed to compete “to the end’’ even if he loses Indiana, although most observers believe losing Indiana would be the end. If Trump wins the state, he will be on track to secure the 1,237 pledged delegates needed to lock down the nomination after the last big batch of primary ballots are cast June 7.

Cruz attempted to inject a sense of excitement into his campaign last week by picking Fiorina as a running mate — a highly unusual move for someone trailing badly in a nominating race. It seemed only moderately more effective in stirring media attention than a short-lived, muddled pact with third-place Republican John Kasich to divvy up states in an effort to block Trump.


Cruz also attempted to endear himself last week to basketball-crazed Indiana voters by holding a rally in the gym where the iconic sports movie “Hoosiers” was filmed. But while quoting from a scene in the movie, Cruz referred to the hoop as a “ring.”

Trump last week won the endorsement of Bobby Knight, the beloved former Indiana University basketball coach, and on Monday he was backed by Gene Keady, the former longtime coach of the state’s other basketball powerhouse, Purdue University.

Cruz gained the endorsement Friday of the state’s governor, Mike Pence, but Trump has led consistently in polls. An NBC News-Wall Street Journal-Marist poll released on Sunday had Trump up 15 points over Cruz. The poll also found the Cruz-Kasich alliance had backfired: 58 percent of people said they did not like their bargain.

At this stage, Trump, with 996 delegates, is the only candidate remaining with a shot at winning the nomination outright. Of the 57 delegates in Indiana, 30 go to the statewide winner; the rest are allotted by congressional district. If Trump captures them all, he would need just 41 percent of the remaining delegates available on the primary calendar to win the nomination.

“It really is like dominos around the winner,” said Scott Reed, who managed Bob Dole’s 1996 presidential campaign and is now the senior political strategist at the US Chamber of Commerce. “Once they start falling you can’t stop it. Winning breeds more winning. And that’s what Trump is showing.”


Clinton, meanwhile, has built up a sizable delegate lead over her rival in the Democratic contest, collecting 2,165 to Sanders’s 1,357, according to the Associated Press delegate tracker. A candidate needs 2,383 votes to secure the Democratic nomination.

Clinton outraised Sanders in the money race for the first time in 2016. The former secretary of state brought in about $26.4 million for her primary campaign in April, according to her campaign. Sanders raised $25.8 million in the same month, a steep drop from his March haul of $44 million.

Yet Sanders remains defiant even as he acknowledged Sunday that he faces a “tough road” to winning the nomination.

“The convention will be a contested contest,” he said, speaking at a press conference in Washington before heading to campaign in Indiana. He urged so-called superdelegates — the elected and other party leaders who are free to back the candidate of their choice — to shift their support to him from Clinton.

“When you have poll after poll nationally saying that Sanders can defeat Trump by in some cases a much greater margin than Clinton, I think it is worth paying attention to that,” Sanders said.

Yet Sanders would need to convert a dramatic number of superdelegates to his cause — far more than President Obama persuaded to ditch Clinton to clinch the nomination in 2008. Currently, only 39 superdelegates have pledged support to Sanders, while more than 500 back Clinton.

Sanders is hoping to notch another win Tuesday in Indiana, but even if he does, Clinton will still win a large number of delegates because Democrats award them proportionally.


“I think it’s going to be a close call . . . but I think she’s going to pull it out,” said Katie Blair, a women’s rights activist from Indianapolis who is volunteering with the Clinton campaign.”

She called Sanders’ vow to stay in the race “unfortunate.”

“Math is math. He doesn’t have the numbers,” she said. “I feel like what he’s doing is really dividing the party and I hope he gives it up soon before it’s more divisive. We need to start on the real threat, which I think is Trump.”

James Pindell of the Globe staff contributed to this report. Matt Viser can be reached at matt.viser@globe.com. Follow him on Twitter @mviser.