The two Democrats argued that Trump committed obstruction of justice, an impeachable offense, when he asked former FBI director James Comey to stop the investigation into Michael Flynn, the disgraced national security adviser who resigned in February, though the White House denied the claim. Trump later fired Comey, who was leading the agency's investigation into Russia's interference in the 2016 election and looking into whether the Trump campaign was in contact with the Russian government.
"Every day, Democrats, Republicans, and the entire world are shocked by the latest example of America’s amateur president. Ignorance accompanied by a refusal to learn. Lack of impulse control, accompanied by a refusal to have his staff control his impulses," Sherman said in a statement. "But the Constitution does not provide for the removal of a president for impulsive, ignorant incompetence. It does provide for the removal of a president for high crimes and misdemeanors."
At least 18 Democrats and two Republicans have mentioned the possibility of impeachment in the last couple of months. And they're not the only ones thinking about whether Trump could be removed from his position: A national poll conducted by the Democratic firm Public Policy Polling in May found that 48% of respondents support the idea of impeaching Trump, while 41% oppose it.
But how does impeachment work and what does it mean for the Trump White House? Ahead, we explain everything you need to know about the impeachment process, and whether it's possible President Trump could be removed from his position.
What is impeachment?
On the most basic level, impeachment is a procedure used by Congress to remove an elected official from their post. It has typically been associated with the presidency, but it has also been used at the local level, like in the case of former Illinois Gov. Rod Blagojevich.
It's a difficult process during which a sitting president is charged with "treason, bribery, or other high crimes or misdemeanors" and, if convicted, is subsequently removed from the position.
While it may seem like a strictly legal or judicial process, it's actually not. Impeachment is highly political — which is one reason it's so difficult to see the process all the way through.
How does it work?
Impeachment is divided into three steps.
First, the House of Representatives formally brings charges against the president. They need a simple majority to pass an article of impeachment. (Each article constitutes a charge.)
The second step in the process is to hold a trial in the Senate, which would be presided over by the chief justice of the U.S. Supreme Court (as of now, Justice John Roberts holds that title).
The third step is for the Senate to come up with a two-thirds vote in favor of convicting the president on any of the counts presented. If convicted on any count, the president would be removed from office and the vice president would ascend to the position.
The last step is the most difficult: Two-thirds of the Senate equals 67 votes, which is an incredibly high threshold, even when a party controls the majority of the upper chamber.
What type of charges can lead to impeachment?
While treason and bribery are two specific crimes outlined in the Constitution, it gets a little murky when we talk about "other high crimes or misdemeanors."
When the House tried to impeach Supreme Court Justice William O. Douglas in 1970, Rep. Gerald Ford said, "An impeachable offense is whatever a majority of the House of Representatives considers it to be at a given moment in history." His words technically still hold true today.
According to the Constitution, the House has "the sole Power of Impeachment." So if we really think about it, members of Congress could bring up whatever charges they see fit. After all, the impeachment process is not a judicial one. The standards for evidence, and even what constitutes a charge in itself, can differ from what would hold water in a court of law.
Has any president ever been impeached?
Remember how we said that third step is the most difficult one? Well, Johnson was acquitted by just one vote in the Senate on all three counts brought by the House. The Clinton margin was even broader: He was acquitted 55-45 and 50-50 on each count against him.
The only person to ever come close to being removed from office through this method was President Richard Nixon. But as you probably know, he resigned before the House could vote on the impeachment articles.
Has Trump done anything that could lead to impeachment?
No. But as the news relating to Comey and Flynn has surfaced, legal analysts have said Trump could be charged with obstruction of justice — either by the Justice Department or Congress. After all, this was one of the charges brought against Clinton (the other was perjury).
Calls for an obstruction of justice charge boil down to the fact that Trump allegedly tried to persuade Comey to drop an active federal investigation against Flynn. Other people also point out that the president fired the man currently investigating whether the Trump campaign colluded with Russia to influence the 2016 presidential election.
However, it's up to Congress and the Department of Justice to gather potential evidence and determine whether this charge would stand.
How likely is it that he will be removed from office?
It's highly unlikely. Johnson, Nixon, and Clinton all faced a Congress controlled by their rival party, but in Trump's case, the Republican Party controls both the House and the Senate.
Unless some extremely damning evidence comes to light, it's almost impossible that the Republican-controlled Congress will try to remove Trump from office. Not only has he remained popular with his base, but not enough Republicans have publicly criticized the president to suggest they would be on board with impeachment.
This story was originally published on May 17, 2017 and has been updated.