Vice President Mike Pence has reportedly “not ruled out” invoking the 25th Amendment to remove President Donald Trump from office, following this week’s attack on the US Capitol building by hundreds of Trump supporters that resulted in five deaths and the destruction of federal property. On Jan. 7, Business Insider reported that Pence wouldn’t seek the 25th Amendment.

Immediately following the riot, lawmakers, cabinet members and a US trade group began calling for Pence to invoke the 25th Amendment. House Democrats have also confirmed that they will begin impeachment proceedings Monday. Nearly 240 Washington lawmakers — 38 Democratic Senators and 199 Representatives from both parties — have backed the proposal, with days to go before President-elect Joe Biden is sworn into office.

“There is growing momentum around the invocation of the 25th Amendment, which would allow the vice president and a majority of the Cabinet to remove the president for his incitement of insurrection and the danger he still poses,” House Speaker Nancy Pelosi said Friday.

Although Pence hasn’t made any public statement about invoking the 25th Amendment, CNN reported Saturday that Pence wants to leave the option open in case Trump becomes unstable, citing a source close to the vice president. Pence is also concerned about Trump’s behavior if the 25th Amendment or impeachment occur, potentially leading to actions that may endanger the nation, according to the CNN report.

Pence and Trump haven’t spoken since Wednesday morning before the attacks, sources told CNN and The New York Times.

What does the 25th Amendment do and how is it different from impeachment? What could happen if the 25th Amendment isn’t invoked? How has Trump been affected by the 25th Amendment before? We’ll explain everything below, including where the situation stands now.

What is the 25th Amendment to the US Constitution?

The 25th Amendment of the US Constitution pertains to the president’s ability to perform the duties of office and what happens in the event that the commander in chief can no longer do his or her job. It empowers the vice president — in this case, Pence — to temporarily assume the powers of presidency, enabling a smooth transition of power in an emergency.

The amendment also allows the president to nominate a vice president if there’s a vacancy.

Read more: FBI posts on Twitter, Facebook seeking help IDing people involved in Capitol Hill violence

The part of the 25th Amendment now under discussion generally relates to Section 4, which would allow the vice president and a majority of the president’s cabinet or a group designated by Congress to declare in writing to the Senate president pro tempore and House speaker that the sitting president is unable to perform the duties of the office. This immediately makes the vice president the acting president.

The president can resist this effort by the vice president and Congress, however, declaring him or herself fit for office in official writing. From there, the vice president and those supporting impeachment have four days to disagree, or the sitting president resumes the presidency. If they disagree, Congress can settle the matter with a vote.

What could happen if the 25th Amendment is not invoked?

The 25th Amendment requires the vice president and Cabinet members to support and initiate the invocation. With Cabinet members resigning and Pence rebuffing demands to begin 25th Amendment proceedings, House Democrats are preparing to start the often lengthy process to impeach Trump for the second time in his four-year term. Here are all the details we know, including how likely impeachment is to come to a vote and what the outcome could mean for Trump even after Biden is sworn in.

Why lawmakers want to remove Trump ahead of Biden’s inauguration

As chaos erupted on Capitol Hill, lawmakers, business leaders and others immediately began calling for the president’s removal from office. Earlier in the day, Trump had told supporters at a rally nearby that “We will never give up, we will never concede.” Trump’s tweets, some of which were deleted or blocked, continued to spur the crowd.

“We’re going to walk down Pennsylvania Avenue … and we’re going to the Capitol,” Trump said at the rally. Afterward, supporters marched to the Capitol, where they later broke past barricades and entered the building. Hours passed as constituents and lawmakers urged Trump to call for the mob to stand down.

Ahead of the impeachment talks, officials in the Trump administration said that Pence, and not Trump, had approved an order to deploy the Washington, DC National Guard. This authority is traditionally reserved for the president.

Trump eventually gave a brief taped statement telling the rioters to go home, calling them “special people,” adding, “We love you,” while continuing to circulate false claims of voter fraud, as he has done for months.

As night fell, social media cracked down on Trump, flagging and deleting multiple posts, as well as placing temporary locks on the president’s accounts.

On Thursday morning, Trump committed to an “orderly” transition of power, and on Thursday night, condemned the riots he has a hand in inciting, by way of a video posted to Twitter. On Friday, Twitter permanently banned Trump’s account “due to the risk of further incitement of violence.”

What would it take to enact the 25th Amendment?

The invocation of the 25th Amendment is considered extraordinary (see below for when it’s been used) and the use of the amendment’s Section 4 is unprecedented: A variety of conditions must come together for the vice president to assume the duties of the president this way.

For Section 4 of the 25th Amendment to take effect, the vice president would need to secure the support of a majority of the department heads and then alert congressional leaders. Alternatively, Congress can designate another body instead of the cabinet. Following the vice president’s notification of congressional leaders, the president can request the return of his presidential powers.

In the event of the 25th Amendment being invoked, it would mean Pence would assume Trump’s presidential responsibilities. Trump could then declare to the House speaker and the president pro tempore of the Senate that there is “no inability” for him to govern. At that point, it would be up to Congress to decide on the matter within 21 days, which would pass the Jan. 20 date when Biden takes office, meaning Pence would hold onto the presidential powers till Biden takes over.

Congress is not in session and would need to be called back, if it came to that. Every sitting senator would have to unanimously agree.

This isn’t the first time Congress has considered using the 25th Amendment against Trump

The 25th Amendment has been discussed before during Trump’s presidency. On Oct. 1, Trump announced on Twitter that he and first lady Melania Trump had tested positive for COVID-19.

Following his coronavirus diagnosis and hospitalization, Pelosi introduced legislation that would allow Congress to enact the 25th Amendment if the president became incapacitated, although she insisted at the time that the legislation wasn’t specifically aimed at Trump.

When released from the Walter Reed National Military Medical Center, Trump, while still under physician supervision and treatment with the steroid dexamethasone, abruptly stopped stimulus check negotiations, only to reinstate them hours later, and offer a stimulus package that ultimately fizzled out. At the time, congressional Democrats discussed invoking the 25th Amendment, but didn’t bring the matter to a vote.

Has the 25th Amendment ever been used before?

Section 4, the portion largely referenced throughout the week, has never been enacted, only coming close once during an attempted assassination of President Ronald Reagan in 1981.

Congress approved the 25th Amendment in 1965. It was ratified and certified as an amendment the following year by President Lyndon Johnson.

The first use of the other sections of the 25th Amendment was in 1973 when President Richard Nixon nominated Gerald Ford to replace Vice President Spiro Agnew, who had resigned. The amendment was used once more when Nixon resigned and Ford assumed the presidency and chose Nelson Rockefeller to fill the vice presidency.

Most recently, President George W. Bush twice invoked the 25th Amendment to temporarily transfer the powers of the presidency to Vice President Dick Cheney while Bush underwent colonoscopies under anesthesia, first in 2002 and then again in 2007. In 1985, his father, then-Vice President George H. W. Bush, received 25th Amendment authority from President Ronald Reagan.