After weeks of focusing on a group of current and former elected officials in his search for a running mate, Donald Trump is increasingly intrigued by the idea of tapping retired Lt. Gen. Michael T. Flynn in order to project strength and know-how on national security, according to four people familiar with the vetting process.

Flynn, 57, a registered Democrat but fierce critic of President Obama, previously ran the Defense Intelligence Agency.

The persons, who spoke with The Washington Post on Saturday, requested anonymity to discuss their private conversations in recent days with Trump’s confidants and campaign aides.

The turn toward a military figure is being driven by Trump himself rather than by his advisers, the people said, and comes as the real estate mogul is telling his friends that national unrest may demand a “tough and steady” presence alongside him on the ticket. In Flynn, they added, Trump believes he would have a partner whom he trusts, based on their close working relationship over the course of the campaign on policy. And he likes a businessman and a general coming to Washington as outsiders.

The shift in how Trump is evaluating his short list is driven by his growing sense that he does not necessarily want or need a running mate who will satisfy Republican insiders, in spite of long saying that he would likely go in that direction. Instead, and after some testy exchanges with GOP lawmakers during his visit to Capitol Hill on Thursday, Trump is more open than ever to going with a nonpolitician.

As multiple people explained, Trump is eager to rally the party around him but sees the convention and other parts of the campaign as integral to that goal, with the vice-presidential nod potentially more important in terms of what it broadly symbolizes to voters.

“Trump-Flynn. I’ve heard him say that, kind of test out the sound of it,” one person said. “I think it’s a brand he finds appealing.”

A Trump campaign spokeswoman declined to comment. A spokesperson for Flynn was unavailable. Flynn’s formal vetting by the Trump campaign was first reported by the New York Post. In an interview with the newspaper, Flynn did not deny that he was under consideration.

“All I would say is that I have been honored to serve my country for the past three decades and look forward to serving in other ways now that I am retired from the U.S. Army,” Flynn said.

Still, Trump remains undecided on his vice-presidential pick, the people said. Indiana Gov. Mike Pence and former House speaker Newt Gingrich, among several others, are being vetted.

Trump is slightly bored by the prospect of going with a traditional Republican. As a longtime celebrity, he has countered that advice with points about the need for surprise and star power. But he is torn about whether his gut instincts should outweigh political calculation.