Rep. Justin Amash's tweets declaring that President Trump committed impeachable offenses have made him an outcast among Republicans, but many of his supporters are excited about what they see as a sign he will run for president as a Libertarian.

The Michigan Republican, 39, is known for defying party leaders on issues such as mass surveillance and government spending. And since Trump took office, he’s been viewed as a possible Libertarian champion in 2020 — a notion amplified by his Saturday remarks.

Amash’s emergence as a possible competitor may have caught Trump’s campaign off-guard.

“Who?" one Trump campaign official said with a chuckle Thursday when asked about a possible Amash run. “Is that a thing?” another asked skeptically. “I had not heard that.”

[Related: Amash gets a primary challenger after impeachment remarks]

A person familiar with Amash’s thinking who spoke with him in recent days told the Washington Examiner that Amash "hasn’t ruled it out” or “pulled any triggers” on a presidential campaign.

Libertarian activist Larry Sharpe, a New York gubernatorial candidate last year, said he spoke twice recently with people close to Amash, who sought advice.

"There are people who are close to the [Amash] campaign who have made calls to members of the Libertarian National Committee and also to me personally, to just talk about the future. But also to talk about Libertarian Party infrastructure,” Sharpe said.

“They wanted to know: Can they make impact as a Libertarian?” Sharpe said, describing the most recent call. “He wants to make impact for a freer America. If Justin Amash believes the Libertarian Party is the best way to do that, I’m sure he will come aboard.”

[Opinion: Get mad at Justin Amash all you want, but he’s still the biggest fiscal conservative]

Sharpe said the most recent caller spoke with him in April about “opportunities” as a Libertarian, including the possibility of third-party runs for the House, Senate, or presidency.

The person familiar with Amash’s thinking who recently spoke with him, however, said it was “extremely, extremely unlikely” that Amash would run for the House or Senate as a Libertarian.

If Amash does run for president, he will be eagerly embraced by Libertarians, who see him as an eloquent evangelist for a political ideology on the decline under Trump.

“He’s terrific,” said former New Mexico Gov. Gary Johnson, an ex-Republican who ran as the Libertarian candidate in 2012 and 2016, taking 3.3% against Trump.

Johnson aligned with the party on most issues, such as legalizing marijuana and avoiding foreign military interventions, but made some members uncomfortable by seeming to embrace gay rights at the expense of the personal freedom of business owners.

Iowa Libertarian Party Chairman Joseph Howe said Amash “comes off as more principled on free market principles” and may be less prone to gaffes. “Amash has probably had more press in the past few days than Johnson in the whole campaign,” he added.

[Related: House Freedom Caucus condemns Amash for backing impeachment]

Howe is leading a national effort to draft Amash, coordinating with the Facebook group Amash 4 President, which has about 800 members.

“When you see something like this, I think it greatly increases the chances he's looking for another party,” Howe said, though he said he believed Amash called for impeachment as “a principled move” rather than a political opportunity.

“It's a long shot, but we don’t need 51% to win, you can force it to the Congress,” Howe said about a possible presidential run.

Amash has supported some Trump policies, such as improving relations with Russia, but is often critical of Trump’s conduct, writing last year he felt “something is not right” after watching Trump’s “bizarre” behavior at a press conference with Vladimir Putin in Helsinki. His Saturday tweets on impeachment prompted a state lawmaker to announce a primary challenge.

“With the bridge burning that's going on, there are a limited number of sensible possibilities” for Amash, said national Libertarian Party chairman Nicholas Sarwark, who added “he's pretty close to the vest in terms of not sharing his plans.”

Richard Winger, a longtime Libertarian, noted Amash introduced legislation in March that would ease ballot access for minor parties. “This tells me he has been interested in minor party problems for several months now,” Winger said.

Amash’s office did not respond to a request for comment. This year, he has indicated he may indeed run. In January, Amash told CNN, “I’d never rule anything out." In January, he sidestepped the question, saying the ideal presidential candidate "wears Air Jordans" — while wearing Air Jordans.

[Related: Amash digs in on Trump impeachment]