Protests are reportedly being organized by a series of progressive groups in the event that President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE decides to fire special counsel Robert Mueller.

The Washington Post reported that more than two dozen progressive groups have started to organize an immediate response if Trump fires Mueller.

The effort involves more than 140,000 people, who have signed on to start protesting within hours in hundreds of cities around the country if Trump makes the decision to fire the man who has levied charges against two former top allies to the president, former national security adviser Michael Flynn and ex-Trump campaign chairman Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE.

ADVERTISEMENT

“It’s pretty rare that people would commit to mobilize around something that we don’t even know will happen, so it shows the energy and passion out there,” said Lisa Gilbert, vice president of legislative affairs for Public Citizen, a Washington-based environmental and government reform organization, according to the Post.

“The reaction will be swift," she said.

People are invited to sign up to protest at trumpisnotabovethelaw.org.

The website says it would be a "constitutional crisis" if Trump fires Mueller and would "demand an immediate and unequivocal response to show that we will not tolerate abuse of power from Donald Trump."

Speculation has been swirling over whether Trump will choose to fire Mueller.

Trump has repeatedly referred to the Russia probe as a "witch hunt" and has denied collusion between his campaign and Russia.

Trump has said he has not plans to fire Mueller, a statement repeated by others at the White House.

A number of Republican lawmakers last week said the president would be wise to let Mueller continue his investigation into Russia's election meddling.

Former Attorney General Eric Holder Eric Himpton HolderThe Hill's Campaign Report: Trump's rally risk | Biden ramps up legal team | Biden hits Trump over climate policy Biden campaign forming 'special litigation' team ahead of possible voting battle Pompeo, Engel poised for battle in contempt proceedings MORE said last week that should Trump choose to fire Mueller, it would be an "absolute red line."

Over the weekend, Trump took to Twitter to lash out at top FBI officials.