Sources told NBC News Friday that Donald Trump was stressed over the circumstances surrounding his choice for running mate even after news of the pick leaked. While in California, separated from family and most aides, Trump worked the phones late into the evening Thursday soliciting advice and sharing his concerns. Sources familiar with the calls said Trump conveyed that he felt "backed into a corner." Another description suggested that Trump was talking it out, but knew that he could not and would not choose a different running mate.

Trump is described as torn because he felt former House speaker Newt Gingrich would be "too volatile" to manage. Trump told others that he had favored New Jersey Governor Chris Christie, but could not choose him because of his own family loyalty. Christie, as U.S. Attorney, prosecuted Charles Kushner, the father of Trump’s son-in-law and close advisor Jared Kushner. Multiple sources said Kushner strongly opposed Christie as the running mate. Working with Christie behind the scenes on the transition team and strategy is one thing, but Kushner could not accept Christie as the running mate.

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Despite a close, long-term friendship with the governor, sources said Trump told others he could not "betray” his family and cause stress for his daughter Ivanka. That made Pence, as described by a source, "the only choice." While Trump likes and respects the Indiana governor, associates of Trump say he also expressed concern that Pence was not a match temperamentally with his brand and style of campaign. However, that is exactly what others in Trump’s circle say makes Pence so attractive.

Pence’s solid experience, mild mannered demeanor and message discipline provide a balance that may reassure uneasy Republicans and donors. News of the Pence pick leaked as Trump officials were in Cleveland trying to quell resistance and did stop attempts to undercut Trump at the RNC Rules Committee. First day reactions to Pence suggest many conservatives are pleased to see him on the GOP ticket. Trump’s gut may have been Christie at first, for his loyalty and political skill. But Trump chose family and professional political advice.

Related: Pence's Traditional GOP Appeal Cuts Both Ways for Trump

Campaign chairman Paul Manafort said flatly that Trump did not attempt to back out of the Pence call Thursday night. "Totally untrue," Manafort said. Campaign spokesman Jason Miller said “there was no wavering.” Campaign officials did say there were evening conversations about delaying the roll-out announcement, but insist that was about the tragedy in Nice, France and not second thoughts from Donald Trump.

Trump had already added to the uncertainty with his own public statements Thursday night. He called into FOX News and insisted he had not made a “final, final” decision. He used that interview to praise all three finalists: Pence, Gingrich and Christie. In that phone interview, Trump also announced his intent to delay the scheduled VP event Friday citing the tragedy in Nice.