David Jackson

USA TODAY

CLEVELAND — As Republicans predicted that Indiana Gov. Mike Pence would be Donald Trump's running mate, the New York businessman said Thursday he is postponing an announcement following the terrorist attack in France.

"In light of the horrible attack in Nice, France, I have postponed tomorrow's news conference concerning my Vice Presidential announcement," Trump tweeted late Thursday after a truck plowed into a crowd celebrating Bastille Day, leaving dozens dead.

While aides to Trump said he has not finalized his selection of a running mate, Republicans familiar with the process predicted it would be Pence.

Pence was in New York City Thursday, where Trump eventually plans to make an announcement.

The Indianapolis Star reported that Trump is planning to pick Pence and that the Indiana governor is prepared to forgo his plans to run for a second term. Television news reports also reported that Pence was the likely pick, though Trump's campaign cautioned throughout the day that the deal is not yet done.

Trump himself told Fox News Channel's Greta Van Susteren Thursday: "I haven't made my final, final decision." He also praised the other two running mate contenders, Newt Gingrich and Chris Christie.

The presumptive GOP nominee spent much of Thursday in California.

Part of Pence's fate will be known by noon Friday — that's the deadline he faces for filing for re-election in Indiana.

Donald Trump Jr. told MSNBC that his father was deciding among Pence, Gingrich and Christie.

"It's down to three," the younger Trump said.

Amid reports about an intense debate among Trump family members and aides as to who should be the running mate, Trump Jr. tweeted: "There's literally none of the drama I'm reading about. 3 great choices. Decision is my father's alone to make!"

Gingrich himself told CNN, "I would not be at all surprised if it was Pence." The former House speaker later told NBC News that "it was a very great honor to be considered" by Trump.

Many Republicans indicated they would welcome Pence's selection as Trump's running mate, noting that the former House member could help the businessman with congressional relations.

"It’s no secret I’m a big fan of Mike Pence’s," said House Speaker Paul Ryan, R-Wis. "We’re very good friends, I have very high regard for him. I hope that (Trump) he picks a good movement conservative. Clearly, Mike is one of those."

Trump's prospective running mate has also taken different positions on free trade and a proposal to at least temporarily bar Muslims from entering the United States.

In a December tweet, Pence said that "calls to ban Muslims from entering the U.S. are offensive and unconstitutional."

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Pence has also been a free trade supporter and backs the Trans-Pacific Partnership, the proposed trade deal with Pacific Rim nations that Trump has pledged to block as a job-killer.

In 2014, Pence tweeted: "Trade means jobs, but trade also means security. The time has come for all of us to urge the swift adoption of the Trans Pacific Partnership."

The Indiana governor recently criticized Trump over his attacks on a judge's "Mexican heritage."

Pence has been busy on Twitter in recent days — touting his accomplishments as governor.

"We've cut costs, lowered taxes & reduced regulations to allow job creators to invest in what matters most — in their businesses & employees," tweeted the former House member, who was elected governor four years ago.

In predicting Pence's selection, Gingrich told CNN: "Mike’s got a lot of strengths and he’s substantially younger." Gingrich also held a Facebook discussion on the "VP selection process" as Trump mulled the possibility of picking him, Pence or Christie.

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Chatter about Pence also increased after the Republicans announced some of the speakers at next week's convention — a list that included Gingrich and Christie, but not Pence, fueling speculation that Indiana governor could be giving the vice presidential speech.

Trump has also spoken in recent days with Christie, a former presidential candidate who was among the first establishment Republicans to endorse the New York businessman.

The New York businessman has also said he might come up with a little-known surprise pick.

Trump Jr. hinted at such a possibility as well during his Thursday MSNBC interview. “You never know — it’s still my dad!" he said, laughing.