Days after supporters of President Donald Trump held a rally in Washington, D.C., that escalated into rioters storming the U.S. Capitol building, many Democrats and some Republicans are calling for Trump to be removed from office.

Lawmakers say Trump urged protesters to march on the Capitol based on unsubstantiated claims of voter fraud, making him unfit to serve as president. Democratic leadership has said if Trump does not resign, they will seek to remove him from office.

There are two ways a sitting president can be removed from office: impeachment and by invoking the 25th Amendment. However, there is little precedent and a lot of gray area surrounding presidential removal, and for the time being, the fate of Trump’s term remains uncertain.

Some Colorado lawmakers have spoken in support of Trump’s removal; Sen. Michael Bennet said via social media that he believes the president is unfit for office and should be removed through the 25th Amendment. Sen. John Hickenlooper echoed those sentiments in a news release, saying he would support any option that would remove Trump from power.

Others have spoken against Trump’s removal so close to the end of his term, including Republican Reps. Lauren Boebert and Ken Buck.

The best-known method to remove a president from office is impeachment, a process by which Congress tries an official for “high crimes and misdemeanors.” Trump has already been impeached once since assuming office, but the Senate voted to not remove him from the presidency.

Impeachment is the primary form of punishment for a sitting president who has violated the law. If a president is impeached for a crime, he cannot face criminal charges for that crime after leaving office.

“Courts are not going to actually convict presidents or even indict presidents while they’re in office,” said Doug Spencer, a law professor at the University of Colorado Law School’s Center for the Study of American Constitutional Law, in an interview Friday with The Durango Herald. “They’ll wait until they leave. And so the only remedy for a president is political, and that means that Congress needs to step up and impeach him.”

The impeachment process takes place in Congress. The House of Representatives drafts articles of impeachment and votes on whether to impeach the president. If the House votes to impeach, the trial is held in the Senate. The president is removed if two-thirds of the Senate votes for his removal, a high threshold intended to prevent impeachment from being a solely partisan exercise.

Seventeen Republicans would need to vote with Senate Democrats to remove Trump from office.

The constitutional language surrounding impeachment is also vague about whether the president has to have violated an actual criminal law, a question that came up during Trump’s first impeachment trial.

It has been suggested Trump could be impeached for inciting violence by encouraging his supporters to march on the Capitol or for a recent phone call in which he threatened legal consequences if the Georgia secretary of state didn’t overturn election results. Regardless of whether he is found guilty of a crime, however, impeachment is possible.

“He just has to do something so egregious that at least two-thirds of the Senate will vote to remove him,” Spencer said.

Trump could also be removed via the 25th Amendment, ratified after President John F. Kennedy’s assassination to establish the presidential line of succession and lay out the process by which a vice president could assume power if the president is unable to serve. Some have called on Vice President Mike Pence to invoke the amendment to remove Trump from office.

To invoke the amendment, the vice president and at least half of the Cabinet must sign onto a written declaration that the president is unable to perform his duties. The declaration would go to the president pro tempore of the Senate, Chuck Grassley, and the speaker of the house, Nancy Pelosi.

The amendment was ratified in response to concerns about presidential incapacitation; however, some have said it should be used in response to Trump’s recent behavior. Trump is not explicitly incapacitated, leading to questions of whether the amendment can actually be invoked considering existing circumstances.

“The controversy in this particular situation is that the word that’s used is that the president is ‘unable’ (to serve),” Spencer said. “So ... a majority of the Cabinet and the vice president would have to send a note to Congress saying that the president is unable.”

The amendment leaves room for interpretation, complicating matters. For instance, some of Trump’s current Cabinet members are acting secretaries, never confirmed by the Senate, and it is unclear how that would affect proceedings.

Also, in the aftermath of Wednesday’s violence, two of Trump’s Cabinet secretaries resigned, complicating any effort to get a majority of the Cabinet to sign onto invoking the 25th Amendment.

“Unable” is also not defined in the amendment; if Pence and the Cabinet declare Trump unable to serve, the president can respond by saying that he is able through a written declaration of his own. If Pence and the Cabinet still assert that the president is unfit, then Congress must decide whether Trump is to be removed from power. That would need to pass Congress with two-thirds of both houses, more votes than to remove a president via impeachment. They would have to hold the vote within 21 days, during which Pence would continue to act as president; that would spell the end of Trump’s term as Biden is set to be inaugurated in less than two weeks.

It would also be possible to remove Trump’s power without invoking the 25th Amendment as his term wanes.

“What might happen is that the members of the Cabinet don’t actually formally invoke the 25th Amendment but they just stop following his orders for the last two weeks, which would have the same effect but without the symbolic gesture,” Spencer said.

At times when Trump has acknowledged his loss, he has expressed interest in another presidential run in 2024. Even if he is removed from office against his will, such a run may be possible.

If Trump is impeached and the Senate votes to remove him from office, a vote will then be put forward that could prevent him from running again. If the vote passes both chambers of Congress with a simple majority, Trump is unable to run.

If he is removed via the 25th Amendment, on the other hand, there is nothing in place that would prevent him from running again in 2024.

Although Trump’s term is in its final days, many are pushing for him to be removed from power to send a message.

“If we don’t send a signal right now that this was unbelievably unacceptable,” Spencer said, “then we are setting ourselves up to normalize what we’ve seen and accept it as an acceptable risk.”

John Purcell is an intern for The Durango Herald and The Journal in Cortez and a student at American University in Washington, D.C.