WASHINGTON - Donald Trump asked Mike Pence to be his running mate and the Indiana governor accepted, a source with direct knowledge tells ABC News.

Pence is believed to be on a plane to New York City right now, ahead of Trump's scheduled announcement of his pick tomorrow morning.

Trump said that the official announcement will come Friday at 11:00 a.m. in New York City.

It became clear that Trump was warming to the prospect of selecting Pence in recent days, since he spent time with him in Indiana on Tuesday and Wednesday.

Pence introduced Trump at a rally in Westfield on Tuesday night, and Trump ended up spending the night in the Hoosier State because his plane had some mechanical issues.

Trump asked his family to fly to Indiana on Wednesday morning for a meeting with Pence at the governor’s house, sources said. The meeting included Trump’s children Eric Trump, Donald Trump Jr., Ivanka Trump and her husband, Jared Kushner. Sources told ABC News that the meeting went very well but that the running-mate job was not offered to Pence at that time.

Speaking to reporters after the meeting, Pence remained mum about his VP prospects. He described the meeting as “just very warm and just one family meeting with another.”