Washington • Democrats vowed Sunday to push forward this week with the third impeachment of a sitting president in history, a move Republicans denounced as a grave and partisan misuse of the Constitution’s power to hold a president accountable.

Democrats showed no sign of slowing down even as one of their few members to oppose impeachment, Rep. Jeff Van Drew of New Jersey, planned to switch parties, and Republican senators lined up to announce their intentions to acquit the president.

The debate about impeachment came as James Comey, the former FBI director, acknowledged that he was wrong when, in a separate investigation of President Donald Trump, he said there were no problems with the warrants used to approve surveillance for an adviser to the president’s 2016 campaign.

Rep. Jerrold Nadler, D-N.Y. and the Democratic chairman of the House Judiciary Committee, which Friday approved articles of impeachment against Trump, said the president deserved to be impeached for pressuring Ukraine’s government to investigate his political rivals and obstructing Congress.

Nadler accused Trump of continuing to solicit foreign help in the 2020 elections and urged Republicans to join with Democrats in the House to impeach him during the vote expected Wednesday, a prospect that appeared increasingly remote.

“This is a crime in progress against the Constitution and against the American democracy,” Nadler said on ABC’s “This Week.” “We cannot take the risk that the next election will be corrupted through foreign interference solicited by the president, which he is clearly trying to do. It goes to the heart of our democracy.”

Republicans defended Trump, insisting that after a nearly three-month investigation, Democrats had failed to prove that the president committed a crime. Rep. Will Hurd, R-Texas, who has criticized the president’s behavior in the Ukraine matter, nonetheless said he would vote against impeaching him.

“My fear is that you weaponize impeachment for political gains in the future,” Hurd said on CNN’s “State of the Union.” “For me, my standard for impeachment has always been a violation of the law.”

Members of both parties, considering Trump’s impeachment in the House a foregone conclusion, turned their attention Sunday to a trial in the Senate early next year.

A group of more than two dozen freshman Democrats in the House is quietly lobbying for Rep. Justin Amash of Michigan, an independent who left the Republican Party this year, to serve as one of the six or more impeachment managers to present the case against Trump during the Senate trial.

Amash has been an outspoken proponent of the president’s impeachment, and the freshman lawmakers believe his selection would be a sign of bipartisanship. The idea, which was first reported by The Washington Post, appeals to moderate Democrats from conservative-leaning districts where the president is popular who are wary of joining in a one-sided impeachment vote and looking for ways to show they pushed for a fair process.

“If he would be willing to do it, it would send all the right signals to have a principled, constitutional conservative front and center in a process that is not supposed to be partisan,” said Rep. Tom Malinowski, D-N.J.

Speaker Nancy Pelosi will have the final say on who serves as managers, which are high-profile, coveted spots for Democratic lawmakers. A final decision is likely early this week, but Pelosi, who has kept tight control over the impeachment process so far, has given no indication that she would be willing to invite anyone but a loyalist to serve as the face of the House impeachment investigation.

A spokesman for Pelosi declined to comment about the possible selection of Amash as an impeachment manager. A person close to the impeachment inquiry said it would be highly unlikely that the speaker would risk appointing Amash when several of her own members are eager to be managers.

Two Republican senators said they had already decided they would vote to acquit Trump.

Sen. Ted Cruz, R-Texas, predicted that the president would be cleared of the charges against him in the Senate.

“I think this is the beginning of the end for this show trial that we’ve seen in the House,” Cruz said. “I think it’s going to come to the Senate. We’re going to have fair proceedings, and then it’s not going anywhere because the facts aren’t there.”

Sen. Lindsey Graham, R-S.C., said he hoped the Republican-led Senate would conduct a short impeachment trial that can be over quickly, without calling numerous witnesses on both sides.

“I think what’s best for the country is to get this thing over with,” Graham said on CBS’ “Face the Nation.” “I’m not trying to hide the fact that I have disdain for the accusations in the process.”

The Republican leader in the Senate, Sen. Mitch McConnell of Kentucky, has also voiced support for a short, dignified trial, even though Trump has privately pushed for a longer process that would allow him and his allies to mount an aggressive defense against what he has repeatedly called “a hoax” being perpetrated on the American people.

Rep. Adam Schiff, D-Calif. and the Democratic chairman of the House Intelligence Committee, Sunday condemned McConnell and others for seeking to conduct a trial without demanding testimony and documents that the White House refused to provide to House investigators.

“They don’t want the American people to see the facts,” Schiff said on “This Week.” “There’s more damning evidence to be had, and they don’t want the American people to see that, and I think that’s disgraceful.”

Sen. Chris Coons, D-Del., said that if the Senate proceeding was “dismissed on the first day, obviously that’s not a full and fair trial.” And he said he was worried about what the president would do if he was not removed from office.

“If the Senate Republican majority refuses to discipline him through impeachment, he will be unbounded,” Coons said on NBC’s “Meet the Press.” “And I’m gravely concerned about what else he might do between now and the 2020 election, when there are no restrictions on his behavior.”

The admission from Comey came just days after the inspector general for the Justice Department, Michael Horowitz, released a report in which he found “17 significant inaccuracies and omissions” in the applications the FBI submitted to a court to surveil Carter Page, a onetime foreign policy adviser on Trump’s campaign. The surveillance of Page was one part of the investigation into the contacts between Russia and Trump’s 2016 campaign.

Comey, who was fired by Trump in May 2017, had previously said the case involving Page was handled in a “thoughtful, responsible way” during the time he was director of the agency.

“I was wrong,” Comey said on “Fox News Sunday.” “The inspector general found significant mistakes, and that is not something to sneeze at. That’s really important.”

Trump seized on Comey’s admission to attack him.

“So now Comey’s admitting he was wrong,” he said on Twitter on Sunday. “Wow, but he’s only doing so because he got caught red handed. He was actually caught a long time ago. So what are the consequences for his unlawful conduct. Could it be years in jail? Where are the apologies to me and others, Jim?”

But Comey noted that the inspector general did not find evidence of the most serious charges of political bias and a “deep state” conspiracy that Trump and his allies have leveled against the FBI in the years since the 2016 campaign.

He firmly defended the FBI, saying the bureau had been proved to be honest and apolitical but “flawed.”

“The inspector general did not find misconduct by FBI personnel, did not find political bias, did not find illegal conduct,” Comey said. “The American people — especially your viewers — need to realize they were given false information about the FBI.”