There has been talk of impeaching Donald Trump even before he took office. Those calls have now come to a head thanks to a growing scandal about the US president’s conversations with Volodymyr Zelensky, his Ukrainian counterpart.
While Mr Trump has denied he did anything improper in withholding nearly $400m in military aid to Ukraine just days before pressuring the country’s president to investigate the son of political rival Joe Biden, his critics have claimed that it proves he is unfit for office.
An official inquiry has now been launched in the House, which is controlled by Democrats. But any attempt to remove Mr Trump would be a bitter, partisan affair, because the president has solid support from his Republican party, which holds a majority in the Senate.
What is impeachment?
Impeachment is the process that the US constitution provides for removing the president, vice-president and other civil officers, such as judges, from office.
What does this mean for Donald Trump?
The Democratic majority in the House opens the door for an attempt to remove Mr Trump from office, even as some Democrats view such a move as an unhelpful distraction from issues such as healthcare and tax cuts.
Democrats have used their control of the House’s various committees to mount investigations into Mr Trump’s administration and his personal affairs. On Tuesday Nancy Pelosi, speaker of the House, instructed six House committees to begin a formal impeachment inquiry.
The Senate, on the other hand, still has a Republican majority. Any successful campaign to remove Mr Trump from office will need to persuade Republican senators to vote against a president from their own party.
The strength of the president’s support among Republican voters means Senate Democrats would probably struggle to persuade enough of their conservative colleagues to win a two-thirds vote.
The situation could still change.
Mr Trump may survive, with his base fired up by the political warfare.
Or he could become the first US president to be removed from office by impeachment.