In a choreographed ritual Wednesday, the House formally appointed seven Democrats to serve as impeachment managers prosecuting the case for removing Trump before the Republican-controlled Senate. The group silently marched two charges of high crimes and misdemeanors, encased in slim blue folders, across the Capitol to set in motion the third presidential impeachment trial in American history.

The proceedings, which will commence Thursday and are expected to last at least several weeks, will play out in a Capitol already rived by partisan politics during a contentious election year. Among the senators who will be sitting in judgment of the president will be four Democrats who are running for president, juggling their campaigns with their duties as jurors in his trial.

The House impeached Trump last month on charges of abuse of power and obstruction of Congress, formally accusing him of pressuring Ukraine to investigate his political opponents while withholding as leverage a nearly $400 million package of military assistance and a White House meeting with the country’s president.

Almost exactly a month later, the House voted Wednesday, largely along party lines, to send its charges to the Senate. Only one Democrat, Rep. Collin Peterson of Minnesota, joined every Republican in voting “no.”

“We are here today to cross a very important threshold in American history,” House Speaker Nancy Pelosi said as she spoke on the House floor before the vote. Regardless of the outcome, she added, Trump would be “impeached for life.”

At the White House, the president denounced the effort to remove him anew as a “hoax” that Republicans would soon debunk — “let’s take care of it,” he told members of the House attending a ceremony in the East Room not long before the vote. Senior administration officials projected confidence, calling theirs an “easy case” and predicting that the Senate would acquit the president in two weeks.

This article originally appeared in The New York Times .