Donald Trump Had Moment of Pause About Mike Pence After Making His Vice Presidential Pick, Sources Say

— -- The deadly attack in Nice, France, and a growing frustration over leaks about his vice presidential pick led Donald Trump to have a moment of pause over his choice of Mike Pence to be his running mate, sources tell ABC News.

Sources close to Trump say he grew increasingly frustrated throughout the day with the news reports leaking his choice of the Indiana governor as his running mate. Trump was even faced with questions about Pence by supporters during closed-door fundraisers in California Thursday afternoon, adding to the frustration and leading him to hesitate, sources say. But at that point, Pence was already in New York.

The plan to get Pence, one of Trump's top three running mate contenders, to New York was put in place on Wednesday. It was then that Trump and Pence spoke by phone and Trump told the governor that he had made his decision and that Pence should get to New York.

Campaign sources say the leadership team spoke with Pence leadership and that’s when they mobilized a plane that landed at Teterboro Airport in New Jersey early Thursday evening.

Though they didn't meet and barely spoke on Thursday, Pence was very much on Trump's mind, sources say.

Shortly after the deadly attack in Nice, Trump tweeted that he was postponing the previously scheduled news conference in which he planned to announce his running mate on Friday morning.

He then had phone interviews with two different Fox News programs: In one, he said he hadn't "made a final, final decision," but in the other he said that he wasn't changing his mind. In the meantime, Pence had already arrived in New York.

Sources tell ABC News that it was only after Trump spoke with his leadership team that he decided to remain with the Pence pick. No calls to other candidates were made.

After the talk with leadership, Trump called Pence and reaffirmed that they were set, sources say.

A senior official with the Trump campaign denied the suggestions of any hesitation on the presumptive Republican nominee's part. "This is completely false. Zero truth to it," Trump Senior Communications Advisor Jason Miller told ABC News.

Far From a Traditional Track

Today's confirmation of his vice presidential pick serves to show once again that Trump is not a traditional candidate.

While most candidates try to keep their running mate pick a secret to heighten the surprise, Trump took the opposite approach, effectively publicly auditioning possible VP picks beforehand.

Trump appeared at a series of events in recent weeks with a number of the reported vice presidential possibilities, including former Speaker of the House Newt Gingrich, New Jersey Gov. Chris Christie and, most recently, Pence.

Either at the events themselves or in subsequent interviews, Trump praised those three and more, openly suggesting at points that they could make great vice presidents.

He also broadcast -- via Twitter, friendly waves to photographers or comments in subsequent interviews -- that he was having meetings with the finalists in the days leading up to the announcement.

Looking Back at 2012

This all comes in stark contrast to the manner in which Mitt Romney tried to hide Paul Ryan from the cameras in 2012 when the then-presumptive Republican nominee was trying to keep his running mate a secret.

At one point, Ryan snuck out of his Wisconsin home using the back door and went down a ravine to the woods behind his house so that he could be picked up at a home at the end of the woods.

Trump was introduced by Pence at a rally in Indiana on Tuesday night, and the real estate mogul ended his speech by speculating about Pence's future.

"I don't know if he's going to be your governor or your vice president -- who the hell knows!" Trump said at the end of the event.