The video above is from a July 2019 interview the day after announcing he was leaving the Republican Party.

Did former Republican-turned-independent congressman Justin Amash drop a hint that he may be launching a third-party run for president? Some people think so based on a tweet last Friday.

Amash, from Michigan, was the only GOP member of Congress to call for an impeachment investigation against President Donald Trump. He said he made the decision after reading the entire redacted report into Russian election interference from former Extraordinary Counsel Robert Mueller.

Mueller concluded there was insufficient evidence to establish a criminal conspiracy between the Trump campaign and Russia, but he also did not exonerate the president on questions of whether he committed obstruction of justice. Trump has denied wrongdoing and characterized the investigation as a "witch hunt."

Amash immediately came under fire from Trump. Several weeks later, Amash -- known for Libertarian values -- announced he was leaving the GOP and would seek re-election to Congress as an independent. He also left the door open for a potential presidential run.

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In a tweet on Friday, Amash called Trump a "threat to liberty in America" and said Trump "appears increasingly unstable."

This may have been a response to tweets from Trump earlier in the day that questioned whether Federal Reserve Chairman Jerome Powell was a bigger enemy to the U.S. than Chinese President Xi Jinping, and a declaration that U.S. companies were "hereby ordered" to get out of China after that country announced it was imposing new tariffs on U.S. goods. Following those tweets, the stock markets tanked, with the Dow Jones ending down more than 600 points.

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"In 2020, we must elect someone who will restore respect for our Constitution and each other," Amash concluded in his tweet.

While most of the replies on Twitter mocked Amash, it got some people wondering if the congressman was setting the stage for a presidential announcement.

"You are #herebyordered to run," tweeted Jake Porter, a 2018 Libertarian candidate for Iowa governor.

"Who would that be, Rep. Amash?" tweeted Elinor Swanson.

One person noted the word "Constitution" in Amash's tweet and wondered aloud if he was telegraphing a potential date for an announcement.

"What are you doing for Constitution Day? Making any....announcements?"

Constitution Day is the anniversary of the signing of the U.S. Constitution, Sept. 17, 1787.

Running for president as a Libertarian would be a threat that could wound Trump, particularly in Michigan, which Trump won over Democrat Hillary Clinton by just over 10,000 votes. More than 172,000 in Michigan voted for Libertarian candidate Gary Johnson -- likely taking some votes from Trump -- while 51,000 voted for Green Party candidate Jill Stein -- likely taking votes from Clinton. Had there been no Green Party candidate, Johnson's effect could have cost Trump Michigan.

Similar stories played out in Wisconsin and Pennsylvania. Without those three states -- which had voted Democrat in each of the previous six presidential elections -- Trump would have lost the race.

The Associated Press contributed to this report.