WASHINGTON (JTA) — Donald Trump postponed the announcement of his pick for vice president, citing the deadly mass killing in France, but also acknowledging indecision over the prospects.

“In light of the horrible attack in Nice, France, I have postponed tomorrow’s news conference concerning my Vice Presidential announcement,” Trump, the presumptive Republican nominee, said Thursday evening on Twitter.

A truck rammed into a crowd in Nice during celebrations marking Bastille Day, the French indepence day, killing at least 77 people.

Trump was set to announce the pick at 11 am Eastern Time in New York. Reports said he was ready to pick Indiana Gov. Mike Pence, but speaking to Fox News Channel after his tweet citing the Nice killings as a pretext for the postponement, he said he was not yet sure. He described the dilemma of having to choose between Pence, Newt Gingrich, the former speaker of the U.S. House of Representatives, and New Jersey Gov. Chris Christie.

“I haven’t made my final, final decision, I mean, I’ve got three people that are fantastic,” he said.

Trump is cutting it close; running mates are usually in place by the launch of conventions. The Republican National Convention begins on Monday.