The House speaker, Nancy Pelosi, has announced she will call a vote on Wednesday to refer articles of impeachment approved last month to the Senate.

The Senate majority leader, Mitch McConnell, subsequently announced that the chamber would take up “housekeeping” items relating to impeachment, possibly including the swearing-in of senators for the trial, later this week and would probably hold opening arguments next Tuesday.

A two-thirds majority of senators would be required to remove Trump from office, which is not seen as likely.

“The president and the senators will be held accountable,” Pelosi said in a statement.

The House judiciary committee chair, Jerry Nadler, told reporters after a morning caucus meeting that Republicans in the Senate must now conduct a “fair” trial.

“The question is, do the Republicans all want to vote to insult the American people?” Nadler said, “to insult the intelligence of anybody watching and to say, ‘We’re going to have a cover up and not a fair trial’?”

Pelosi had delayed relaying the articles of impeachment to the Senate, calling on McConnell to clarify the rules of the trial before she designated prosecutors in the case.

Q&A How do you impeach the US president? Show Article 1 of the United States constitution gives the House of Representatives the sole power to initiate impeachment and the Senate the sole power to try impeachments of the president. A president can be impeached if they are judged to have committed "treason, bribery, or other high crimes and misdemeanors" – although the US Constitution does not specify what “high crimes and misdemeanors” are.

The formal process starts with the House of Representatives passing articles of impeachment, the equivalent of congressional charges. According to arcane Senate rules, after the House notifies the Senate that impeachment managers have been selected, the secretary of the Senate, Julie Adams, tells the House that the Senate is ready to receive the articles. Then impeachment managers appear before the Senate to “exhibit” the articles, and the Senate confirms it will consider the case. The presiding officer of the Senate notifies the supreme court chief justice, John Roberts, of the impending trial. Roberts arrives in the Senate to administer an oath to members. The presiding officer will then administer this oath to senators: “I solemnly swear that in all things appertaining to the trial of the impeachment of Donald Trump, now pending, I will do impartial justice according to the constitution and laws, so help me God.” The Senate must vote on a resolution laying out ground rules for the trial including who the key players will be, how long they will get to present their cases and other matters. After the Senate is “organized”, the rules decree, “a writ of summons shall issue to the person impeached, reciting said articles, and notifying him to appear before the Senate upon a day and at a place to be fixed by the Senate”. A president has never appeared at his own impeachment trial. Trump will be represented by the White House counsel, Pat Cipollone, and his personal lawyer Jay Sekulow, among others. After the oath, the trial proper will begin. Senators may not speak during the proceedings but may submit written questions. The question of witnesses and other matters would be decided on the fly by majority vote. A time limit for the proceedings will be established in the initial Senate vote. The senators will then deliberate on the case. In the past this has happened behind closed doors and out of public view. The senators vote separately on the two articles of impeachment – the first charging Trump with abuse of power, the second charging him with obstruction of Congress. A two-thirds majority of present senators – 67 ayes if everyone votes – on either article would be enough to convict Trump and remove him from office. But that would require about 20 Republicans defections and is unlikely. The more likely outcome is a Trump acquittal, at which point the process is concluded. Two presidents have previously been impeached, Bill Clinton in 1998, and Andrew Johnson in 1868, though neither was removed from office as a result. Richard Nixon resigned in 1974 before there was a formal vote to impeach him. Tom McCarthy in New York

In the immediate wake of Trump’s impeachment last month, McConnell argued that the Senate should not spend long on a trial, saying: “Obviously, I think we’ve heard enough.”

Earlier this week, Trump himself called on senators to dismiss the case quickly.

But support among a moderate bloc of senators for witness testimony at the trial has slowed whatever momentum there once was behind a quick dismissal. The second-ranked Republican in the Senate, John Thune of South Dakota, said on Tuesday he would be “surprised” if the body moved abruptly to dismiss the case.

“I would bet against it,” Thune said.

Under Senate rules, articles of impeachment against a president are prosecuted at trial by designees known as House managers. Pelosi stopped short of naming managers on Tuesday morning. They will be named in the resolution to be passed on Wednesday.

The president has the option of appearing in his own defense but was expected to send a legal team headed by the White House counsel, Pat Cipollone.

“We need to see the arena in which we are sending our managers,” Pelosi had said in a news conference last Thursday, explaining the delay. “Is that too much to ask?”

But under growing pressure from fellow Democrats to move the process ahead, Pelosi took the decision to refer the articles without McConnell supplying a substantive description of the rules in question.

Hakeem Jeffries, chairman of the Democratic caucus, said Pelosi’s decision to delay sending the articles of impeachment to the Senate “created space” for moderate Senate Republicans to push McConnell to allow witness testimony during the trial.

“We are three-quarters of the way to seeing a fair and comprehensive trial in the Senate as it relates to Donald Trump’s abuse of power,” Jeffries said. “That alone is a tremendous objective that has been accomplished.”

Trump was impeached on two articles, for abuse of power and obstruction of Congress, on 18 December. He denies any wrongdoing.