Republican presidential candidate Donald Trump speaks during a campaign stop May 1 in Fort Wayne, Ind. (Darron Cummings/AP)

INDIANAPOLIS — It was the day before Indiana's crucial Republican presidential primary, but Donald Trump was focused on only one person: Hillary Clinton.

The confident business mogul strode into Shapiro's Delicatessen here Monday for a quick lunch. He autographed one man's $50 bill with a black Sharpie. He vowed that Tuesday's primary would spell the end of GOP rivals Sen. Ted Cruz and Ohio Gov. John Kasich. He trumpeted, three separate times in five minutes, a new Rasmussen poll showing him leading Clinton nationally.

The general election, Trump said, has "already started."

Then he and two aides sat down at a table for lunch with author Edward Klein, perhaps best known for his series of bombshell books spreading rumors and innuendo, much of it discredited, about the Clintons. Klein's latest writings have centered on former secretary of state and senator Hillary Clinton's personal health and former president Bill Clinton's sexual adventures.

It could not be determined what the foursome discussed over their Reuben sandwiches — Klein, who rode to and from the restaurant in the same vehicle as Trump in a Secret Service motorcade, said he is following Trump around for a couple of days to gather material for a new book. But the visit with Klein comes as Trump promises to debut new attacks on the stump about the Clintons.

Answering a few questions from reporters as he made his way to the lunch table, Trump said he was eager to move on to the general election. "I would like to get onto Hillary," he said. "We've beaten all these [Republican] folks."

Asked whether a loss in Indiana should end Cruz's campaign, Trump said, "I think it should. I really do."

Trump dismissed the endorsement of Cruz by Indiana Gov. Mike Pence, who is popular with Republicans here, by noting it was less than full-throated and suggesting the governor was backing Cruz merely as a favor to party power brokers.

"His endorsement was really a very weak one, and it was, you know, very good for me," Trump said. "He was very nice, the governor. But he’s under a lot of pressure from his donors, the special interests, and I understand that."

Trump previewed "some unbelievable endorsements" he would receive in coming days, but offered no further clues. Asked whether he had spent the weekend calling Republican senators, governors and other officials to gather support, Trump said he had not.

"I just don’t know if it matters," Trump said.