Donald Trump and Indiana Gov. Mike Pence. REUTERS/John Sommers II Donald Trump is expected to pick Indiana Gov. Mike Pence as his running mate, Capitol Hill newspaper Roll Call reported Thursday morning.

Multiple reports later Thursday said Trump had called Pence to offer him a place on the ticket, and Pence accepted.

According to The New York Times, several sources said Trump was preparing the announcement with Pence, which was expected Friday morning.

Trump has since postponed the announcement in light of the Bastille Day attack in France.

A senior Trump communications adviser cautioned on Twitter earlier Thursday that Trump had not yet made an official decision on his vice presidential choice.

Later on Thursday evening, however, reporters from CNN, NBC, and ABC, among others, noted that Trump had called Pence to offer him the running mate spot, and he accepted.

Speculation about Trump choosing Pence as his running mate took off on Thursday when the Republican National Convention released its list of speakers. Pence was notably absent from the list.

Pence is a former congressman who has been called a "rising star" among conservatives. He chose to run for governor of Indiana in 2012 rather than seek the Republican nomination for president. He's currently locked in a reelection race for the governorship.

Pence would give Trump credibility with social and movement conservatives and could help him gain an edge in what could be a close race in Indiana and throughout the Rust Belt — a stretch in which Trump must perform well.

Trump had been meeting with prospective running mates this week ahead of the Republican National Convention in Cleveland next week.

Pence beat out New Jersey Gov. Chris Christie, former House Speaker Newt Gingrich, and several others for the running mate spot.

Allan Smith contributed to this report.