INDIANAPOLIS — Ted Cruz said Wednesday morning that he would make a “major announcement” at an afternoon rally here, a day after his drubbing by Donald Trump in Republican presidential primaries in five East Coast states.

Cruz declined to say what his announcement would be. It comes as Cruz, who is in desperate need of a way to gain ground on Trump, is vetting potential vice presidential running mates. He joked Tuesday night that he would have an announcement on that front, before saying in jest that Democratic candidate Hillary Clinton had picked Trump as her running mate.

Trump and Cruz were quickly setting their sights on Indiana on Wednesday, where Trump is seeking a knockout blow and Cruz was making a last-gasp effort to survive.

Trump will return to the Hoosier State to hold an evening rally after delivering a foreign policy address in Washington that his team hopes will make him appear more presidential. He will be joined in Indiana by longtime Indiana University basketball coach Bob Knight, who is a fan favorite here.

Cruz, who has spent the past few days in Indiana trying to get a head start on Trump and move swiftly past his humiliating Tuesday defeats, planned to campaign at a restaurant Wednesday morning before the afternoon rally.

Looming over the race is the question of whether Gov. Mike Pence will publicly back Trump, Cruz or no one. The governor met with both candidates last week.

“He may not endorse — I don’t think he’ll endorse anybody, actually — and he may endorse us, I don’t know,” Trump said on CNN on Wednesday morning. He added that he thinks Pence will either endorse him or no one.

Indiana is the only state holding a Republican primary next Tuesday. Trump and Cruz are expected to spend much of their time campaigning here. A loss for Cruz would deal a catastrophic blow to his struggling campaign, which was set back immensely by his poor showing Tuesday.

The third remaining candidate, Ohio Gov. John Kasich, has stopped actively campaigning in Indiana, clearing the way for Cruz to square off against Trump one on one. In exchange, Cruz is clearing the way for Kasich to face Trump in Oregon and New Mexico. Kasich plans to stump in Oregon on Thursday.

The Cruz-Kasich deal has been unsteady, and it’s not clear whether it will have the intended effect of isolating and defeating Trump in three key states.

Polls show Trump and Cruz in close competition in Indiana. In a speech Tuesday night at the Hoosier Gym in Knightstown, where the movie “Hoosiers” was filmed, Cruz declared to supporters: “Tonight this campaign moves back to more favorable terrain.”

Cruz will enter the next week badly wounded by two straight weeks of East Coast blowout losses where he mostly finished third behind Trump and Kasich. On Tuesday, Trump swept Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island. In all but Pennsylvania, Cruz finished last.

According to the Associated Press’s latest delegate count, Trump has nearly a 400-delegate lead over Cruz and is nearly 800 ahead of Kasich.

Trump called his Tuesday sweep the “biggest night” of the campaign, confidently predicting that he could capture the 1,237 delegates needed to clinch the Republican nomination outright. He also suggested during a question-and-answer session with reporters at Trump Tower on Tuesday evening that Cruz and Kasich were doing the party harm by remaining in the contest.

“I consider myself the presumptive nominee, absolutely,” Trump said. He suggested that Cruz and Kasich exit the race because “they have no path to victory at all.”

He added: “The best way to beat the system is to have evenings like this, where you get record-setting votes.”

Responding to reports that Cruz is vetting Republicans, including rival-turned-supporter Carly Fiorina, to be his vice presidential running mate, Trump said Wednesday morning that it was not a good idea.

“I think it hurts him. I can’t imagine he does it,” the mogul said on “Fox and Friends.” “First of all he shouldn’t be naming anybody because he doesn’t even have a chance.”

Cruz nodded at the vice presidential intrigue surrounding him Tuesday night, saying he had an announcement. But the announcement — that Clinton had tapped Trump as her running mate — was made in jest.

During a rally in Indiana last week, Trump put the air-conditioning maker Carrier at the center of his pitch. He is expected to continue doing so. The company has announced that it plans to move jobs from Indianapolis to Mexico. Trump said that as president, he would subject such a move to a tax penalty. He has mentioned Carrier in other states, too.

Trump also has bragged about Knight’s endorsement on the campaign trail for days.

“He’s tough, he’s sharp and he wins. And the people of Indiana love him,” he said Tuesday.

Cruz repeatedly tried to link Trump to Clinton on Tuesday night, signaling that he plans to try to blur the distinction between them on several policy and political fronts during the next week.

Clinton and Trump are “flip sides of the same coin,” argued Cruz, who accused Trump of holding Clinton-like views on health care, foreign policy, immigration and other issues.

Trump has been an outspoken critic of Clinton. He has referred to her on the campaign trail as “Crooked Hillary.”

Indiana awards 57 delegates to the Republican National Convention on a winner-take-all basis by congressional district and statewide.

DelReal reported from New York. Katie Zezima in Washington contributed to this report.