US Republican presidential candidate Donald Trump at a campaign event at The Palladium at the Center for Performing Arts in Carmel, Indiana, on May 2. Reuters/Aaron Bernstein

Shifting swiftly to the general election, Donald Trump says he has narrowed his list of potential running mates to "five or six" people and doesn't want to accept public money to finance a fall campaign against likely Democratic nominee Hillary Clinton.

But in a break from recent major party nominees, Trump does not plan to invest heavily in a data-driven effort to target voters in the fall campaign. Despite pressure, the billionaire businessman also doesn't expect to release his tax returns before November, citing an ongoing audit of his finances. He said he would release them after the audit ends.

"There's nothing to learn from them," Trump told the Associated Press in an interview Tuesday. He also has said he doesn't believe voters are interested.

Trump's comments came as he begins to prepare for a long, expensive general-election campaign. His two remaining Republican rivals suddenly dropped out of the race last week, anointing him the party's presumptive presidential nominee faster than even the confident candidate expected.

As part of his general-election planning, Trump told the AP at his office in New York, he is moving aggressively to identify a running mate with deep political experience. While he would not provide a full list of names, he did not rule out Gov. Chris Christie of New Jersey, the former rival whom he has already tapped to head his transition planning.

Trump's campaign manager, Corey Lewandowski, is running the vice presidential vetting effort "with a group," Trump said, that includes former competitor Ben Carson and Trump. "Honestly, we're all running it. It's very much a group effort," Trump said.

A first-time political candidate, the celebrity businessman said there was no need for another business executive on the Republican ticket and he wanted a running mate who could help him pass legislation as president. By joining forces with a political veteran, Trump would also signal a willingness to work with the Republican establishment that he has thoroughly bashed during his campaign.

Ben Carson has been actively supporting Trump's campaign. REUTERS/Carlo Allegri

Trump said he didn't plan to announce his running mate until the Republican National Convention in July, a four-day event that he is planning to remake with a showman's touch.

"The concept of some entertainment from a great singer, a great group I think would be something maybe to break things up," Trump said. "You'll be hearing plenty of political speeches."

In the interview, Trump outlined a general-election campaign that banks heavily on his personal appeal and trademark rallies while spurning the kind of sophisticated data operation that was a centerpiece of Barack Obama's winning White House runs.

"I've always felt it was overrated," Trump said. "Obama got the votes much more so than his data-processing machine. And I think the same is true with me."

He also ruled out for the first time the option of taking public financing for his campaign, money that would have saved him the time-consuming task of raising vast sums but that would have dramatically limited the amount he would have been able to raise.

"I don't like the idea of taking taxpayer money to run a campaign," he said. "I think it's inappropriate."

Trump stunned the political world at every turn during the Republican primary season, prioritizing large rallies over intimate voter interactions in early-voting states and operating with a slim campaign operation. Even as he brings in new staff members for the general-election campaign, he says, his emphasis will continue to be on raucous rallies to put him in front of thousands of voters and generate free media coverage.

"My best investment is my rallies," Trump said. "The people go home — they tell their friends they loved it. It's been good."

The businessman said he would spend "limited" money on data operations to identify and track potential voters and to model various turnout scenarios that could give him the 270 Electoral College votes needed to win the presidency. He is moving away from the model that Obama used successfully in his 2008 and 2012 wins and that Clinton is trying to replicate, including hiring many of the people who worked for Obama.

Corey Lewandowski is leading Trump's vice presidential selection process. AP Photo/Charlie Neibergall

Still, the Republican National Committee has invested heavily in data operations, eager to avoid another defeat to a more technologically savvy Democrat. Trump could make use of that RNC data if he wished.