Articles of impeachment delivered to Senate, triggering historic trial of President Trump Speaker Nancy Pelosi said the House was holding the president "accountable."

House Speaker Nancy Pelosi on Wednesday formally set in motion the process of sending the articles of impeachment against President Donald Trump to the Senate, triggering a historic trial set to begin on Thursday.

At an "engrossment" signing ceremony for the House resolution naming the seven impeachment managers -- the lawmakers who will present the House case as prosecutors at the trial -- Pelosi said the House was doing its "constitutional duty."

"Today, we will make history," she said, "when we walk down -- when the managers walk the hall, they will cross a threshold in history, delivering articles of impeachment against the president of the United States for abuse of power and obstruction of the House."

"This president will be held accountable," she said.

After signing the resolution, she handed out the pens she used to the managers.

Then, marking the somber nature of the occasion, the managers silently walked the articles, in two blue folders, across the Capitol from the House to the Senate, where the House clerk announced their arrival. The Senate will formally accept them on Thursday.

Senate Majority Leader Mitch McConnell announced that the Senate would convene at noon after which the managers will read the articles aloud, Chief Justice John Roberts will be sworn in and he, in turn, will swear in senators to serve as jurors in the case.

"Let me close with this," McConnell said. "This is a difficult time for our country. But this is precisely the kind of time for which the framers created the Senate. I am confident this body can rise above short-termism and factional fever and serve the long-term best interests of our nation.

"We can do this. And we must," he said.

Earlier Wednesday, the House voted 228-193 to formally send the impeachment charges against President Trump to the Senate to begin the third presidential impeachment trial in American history.

The House resolution officially appoints the seven managers, named by Pelosi Wednesday morning.

In the morning, shortly after being named an impeachment manager, House Judiciary Chairman Jerry Nadler submitted the text of a resolution that spells out the managers’ duties.

During the short floor debate before the vote, Minority Leader Kevin McCarthy took aim at the managers appointed by Pelosi, as they sat in front of him, listening.

"By selecting this particular batch of managers, the speaker has further proven she's not interested in winning the minds, the hearts, or even following the Constitution," he said, calling out Nadler, and House Intelligence Chairman Adam Schiff, specifically.

He criticized Pelosi's comments this morning about Trump being impeached "forever," accusing her of playing politics.

"The speaker said, 'The President is impeached forever.' Is this what this is all about?" he said. Pelosi pumped her fist in the air as McCarthy quoted her.

There were about 140 members of the public watching from the galleries.

When it was her turn, Pelosi, standing next to a poster showing the American flag and a quote from the Pledge of Allegiance, ended debate by denouncing Trump's actions and defending the timing of the impeachment proceedings in the House.

"It is a fact that once somebody is impeached, they are always impeached. It cannot be erased. I know you don't like hearing that," Pelosi said to McCarthy.

Trump, she said, "gave us no choice" on impeachment.

"They would have liked us to send this over on Christmas Eve so they could dismiss it. Perhaps they don't know that dismissal is a cover-up."

President Trump, participating in a signing ceremony of an agreement between the United States and China at the White House, observed some Republicans in the audience and directed them to go vote against the resolution.

"It's on the impeachment hoax," Trump said of the resolution. "It's not going to matter 'cause it's going very well, but I'd rather have you voting than sitting here listening to me introduce you. They have a hoax going on over there, let's take care of it."

"Resolved, That Mr. Schiff, Mr. Nadler, Ms. Lofgren, Mr. Jeffries, Mrs. Demings, Mr. Crow, and Ms. Garcia of Texas are appointed managers to conduct the impeachment trial against Donald John Trump, President of the United States, that a message be sent to the Senate to inform the Senate of these appointments, and that the managers so appointed may, in connection with the preparation and the conduct of the trial, exhibit the articles of impeachment to the Senate and take all other actions necessary…," the resolution states, formally naming each impeachment manager.

The resolution goes on to authorize "employing legal, clerical, and other necessary assistants and incurring such other expenses as may be necessary, to be paid from amounts available to the Committee on the Judiciary under applicable expense resolutions or from the applicable accounts of the House of Representatives."

In other words, the costs of the House participation in the Senate trial will be covered by the Judiciary Committee.

The measure also authorizes "sending for persons and papers, and filing with the Secretary of the Senate, on the part of the House of Representatives, any pleadings, in conjunction with or subsequent to, the exhibition of the articles of impeachment that the managers consider necessary."

Pelosi will sign the bill at a 5 p.m. engrossing ceremony in the Capitol, before the managers carry out the ritual of marching across the Capitol to present the bill to the Senate secretary.

Earlier, as she named the managers, Pelosi, with Schiff and Nadler at her side, began by saying "an impeachment will last forever."

Schiff and Nadler will be two of the mangers, Schiff designated by Pelosi as the lead manager.

"This is a very important day for us," she said.

"Time has been our friend in all this," she added, noting what she called the new "incriminating" evidence that has surfaced in the month since the House impeachment vote on Dec. 18, including new documents from Lev Parnas, an associate of Rudy Giuliani, the president's personal lawyer.

Schiff said that bombshell new evidence, revealed by the House just Tuesday night, must be considered by the Senate.

Schiff added that documents will be just as important as any witnesses, citing a letter Giuliani sent Ukrainian President Volodymyr Zelenskiy and what it said about his having Trump's blessing.

"If the Senate wants to see the evidence, they should demand to see the documents," he said.

Democrats further pushed back on the comparison to the Clinton trial precedent, pointing to the fact that during Clinton, the Senate had the full record thanks to the Starr investigation and the House investigation.

Nadler also batted down the early suggestion from Republicans that former Vice President Joe Biden's son, Hunter Biden, should be called, saying he wouldn't be considered a relevant witness.

"It's important for the president to know and Vladimir Putin to know that the American voters decide who are president is. We wouldn't be in this situation had we not waited and insist that there be witnesses and we see documentation," Pelosi said.

Other managers Pelosi named were Reps. Hakeem Jeffries of New York, Val Demings of Florida, House Administration Committee Chair Zoe Lofgren of California, Sylvia Garcia of Texas and Jason Crow of Colorado.

Pelosi said she chose members of Congress with experience as litigators who are comfortable in a courtroom setting and making a strong, evidence-based case.

"The emphasis is making the strongest possible case to protect and defend our Constitution, to seek the truth for the American people," she said.

When asked about the delay in transferring the articles, Schiff said the extra time helped Democrats make the case for a trial in the Senate after Senate Majority Leader Mitch McConnell initially said he would support efforts to dismiss the case.

"If McConnell makes this the first trial in history without witnesses it will be exposed for what it is and that's an effort to cover up for the president," Schiff said.

"Dismissal is cover-up," Pelosi added.

"It is essential we bring this impeachment to stop the president from rigging the next election," Nadler said.

Pelosi ended the announcement by warning that should the Senate fall short of a full trial, it wouldn't overshadow the House's impeachment vote - just the third in American history.

"He has been held accountable. He has been impeached forever. They can never erase that," Pelosi said.

There have been 20 presidential impeachment managers in American history; all of them have been white men.

Pelosi's team has three women: Demings, Lofgren and Sylvia Garcia.

There are two freshman lawmakers on the team: Crow, a former Army Ranger and lawyer, and Garcia.

Crow helped write the pivotal Washington Post op-ed with other freshman in September in favor of impeachment that was seen as turning the tide in favor of impeachment in the caucus. He's the only manager who is not a member of the Judiciary or Intelligence Committees. Demings, the former police chief of Orlando, is on both panels.

Lofgren is a veteran of three impeachments: She was a Judiciary Committee staffer during Watergate, and served on the panel during Clinton's impeachment.

Though the House voted to impeach Trump in December, charging him with abuse of power and obstruction of Congress, Pelosi withheld delivering the charges to the Senate, saying she wanted McConnell to first outline the rules of the trial and commit to bringing key witnesses before the Senate to testify, including former White House National Security Adviser John Bolton.

While McConnell resisted Pelosi's pressure campaign, a number of Senate Republicans have expressed interest in voting to hear from witnesses after the initial opening arguments. And McConnell has ruled out dismissing the charges against Trump at the start of proceedings, a move that Democrats feared would circumvent an airing of the charges against the president.

"The American people deserve the truth, and the Constitution demands a trial," Pelosi wrote in a statement released on Tuesday.

Shortly after word came about the planned House vote, McConnell took to the Senate floor to lambaste what he called an "arbitrary" month-long delay in sending over the articles.

The delay has impacted the plans of the several Senate Democrats running for president, forcing them to adjust their campaign schedules leading up to the Iowa caucuses early next month.

McConnell said arguments in the Senate trial are expected to begin next Tuesday.

Removal from office would require 67 senators voting in favor of conviction, constituting a simple majority of the body. That means at least 20 Republicans would need to turn against the president, assuming all Democrats vote to convict.