WASHINGTON – Democrats who are contemplating impeaching President Donald Trump after they take control of the House of Representatives next month are considering a cautionary tale: what happened the last time a president was impeached.

President Bill Clinton survived, but his top accuser, House Speaker Newt Gingrich, didn't, and it was the Republican Party that lost seats in the next election.

"Impeachment is hell," warned independent counsel Ken Starr, whose exhaustive investigative report on Clinton was the basis for the House vote, taken precisely 20 years ago Wednesday. Starr thought through all that happened in writing his new book, Contempt: A Memoir of the Clinton Investigation. With the benefit of hindsight, he said in an interview, "The better call would have been a resolution of censure," a measure that would have expressed disapproval of the president's actions but left him in office.

Trent Lott, then the Senate majority leader, was one of 45 senators who voted to convict Clinton, but he has second thoughts of his own. "I do think he made mistakes," Lott said in an interview. "But in retrospect, I think it probably should not have been done."

Outraged by allegations of perjury, obstruction of justice and sexual misbehavior leveled against the president, Clinton's political opponents argued that impeachment was the right course for the country. House Republicans impeached Clinton, but the Senate refused to convict him.

There are calls to impeach Trump over allegations that he colluded with Russians during the 2016 campaign, obstructed investigations and violated campaign finance laws by paying hush money to two women. Last week, his former attorney and fixer, Michael Cohen, was sentenced to prison for making those payments to suppress publicity about accusations of sexual trysts. Tuesday, Trump's former national security adviser Michael Flynn was in court, where he asked to postpone his sentencing for lying to the FBI about the Russia investigation.

As Washington waits for special counsel Robert Mueller's report, the I-word is in the air – and memories of the case of Clinton are a major factor in the debate.

More:Clinton impeachment: 20 years later, where are key figures from historic battle?

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Success rate low, unintended consequences high

Republicans who played key roles in impeaching the president 20 years ago warned that the possibility of success is low and the prospect of unintended consequences high. Those lessons reinforced caution among top Democrats, including House Minority Leader Nancy Pelosi, who is likely to be elected speaker in January, and New York Rep. Jerry Nadler, who is likely to chair the Judiciary Committee.

The House vote on Dec. 19, 1998, was just the second time in U.S. history that the House had voted to impeach a president. Both presidents survived Senate trials – Clinton in 1999 and Andrew Johnson in 1868. (In 1974, Richard Nixon resigned in the face of his likely impeachment amid the Watergate scandal.)

Nadler was a junior congressman during Clinton's impeachment. He became one of the president's fiercest defenders, denouncing his impeachment as a "partisan coup d'etat." He is poised to chair the committee that would consider Articles of Impeachment against Trump.

He urged Democrats to proceed with care. The question is not only whether the president committed an impeachable offense, he said, but also whether the offense is so serious that it can convince his own supporters that he should be removed from office. Trump would need to hold 34 of the 53 Republican senators to prevail in a Senate trial.

Two decades ago, when Starr submitted his report, Eric Swalwell was a 17-year-old high-school senior in California. Now he's part of the House Democratic leadership and a member of the Judiciary Committee. The consequences of Clinton's impeachment aren't lost on him, either.

"No one is above the law," Swalwell said in an interview. "But you have to balance that against the reality of whether what you're seeking to do would be successful. If you're just doing it to score political points and you know you would never have support from the Senate, then I don't know if that's good for the country."

For him, he said, there would need to be "an impenetrable case" against the president that commanded bipartisan support and reflected a consensus across the country.

A disruption of democracy

Impeachment is a disruption of democracy, holding officials accountable by overturning the results of an election. In Article II of the Constitution, the founders made impeachment easy, requiring only a simple majority in the House. But they made conviction difficult, requiring two-thirds of the Senate.

They left the grounds for impeachment, of "high crimes and misdemeanors," open to the best judgment of the day.

Historian Jeffrey Engel, co-author of "Impeachment: An American History," calls impeachment "the framers' safeguard, a nuclear option provided to halt tyranny and corruption at the top, to employ a term they would neither have employed or understood."

The accusations against Trump echo those the founders had in mind, he said, especially their fear that a president might be corrupted by foreign influence.

"I think the founders would be surprised that he hasn't already been impeached," Engel, director of the Center for Presidential History at Southern Methodist University, said in an interview. He noted that the polarized politics of today and the solidity of Trump's core support make conviction a distant prospect, whatever the charges.

Count that among the lessons from Clinton's impeachment.

"The No. 1 takeaway I have is that nobody comes out looking good in the end," Engel said. "I'm struck by how all the leaders of the Republican leadership who went after Clinton found themselves resigned or disgraced or both."

The costs for Clinton's accusers were high. Starr, who served as solicitor general and a federal Appeals Court judge, said the controversy that surrounded his role as independent counsel prevented him from being considered for a Supreme Court appointment. Gingrich, who acknowledged he was "stunned" when Republicans lost seats in the 1998 midterms amid the impeachment debate, resigned. Georgia Rep. Bob Barr, who filed the first impeachment charges, saw allegations of his own marital infidelity aired by Hustler publisher Larry Flynt.

"I suppose the lesson there is if you have those sorts of problems, personal problems, you probably ought not to be taking a high-profile stance on an issue like the impeachment," Barr said in an interview, though he argued it was right to impeach Clinton for perjury and obstruction of justice. "It certainly impacted my family, and that was unfortunate."

Those cautions aside, some analysts and some voters assume Democrats will impeach Trump. "It's inevitable," said Michael Steel, a Republican strategist and former aide to House Speaker John Boehner, citing pressure from the Democrats' most liberal voices. "They won't be able to stop themselves."

A 54 percent majority of Americans predicted in a USA TODAY/Suffolk University Poll taken in October that if Democrats won control of the House, they would seriously consider impeaching the president. More than a third of those surveyed, 39 percent, said they supported the idea themselves, including more than two-thirds of Democrats.

Incoming New York Rep. Alexandria Ocasio-Cortez, a leader among the new class of liberal Democrats, said on Capitol Hill that Trump has "far surpassed" the standards Republicans used to impeach Clinton. Would it be premature to impeach Trump? "Not to me," she said.

Billionaire activist Tom Steyer, who is considering a presidential bid, invested millions of dollars in a group called Need to Impeach, airing TV ads that call Trump "dangerous" and his impeachment "a moral responsibility."

During the midterm campaign, Steyer's campaign annoyed some top Democrats who saw it as a distraction at least and damaging at most, especially for candidates in swing districts. Most Democratic leaders, including former President Jimmy Carter, urged the party's candidates to focus on issues such as health care and to defer making pronouncements on impeachment until Mueller filed his report.

Pelosi urged Democratic colleagues who pushed for impeachment to give Mueller the time and space he needs to complete his inquiry. Associates said Pelosi, a California congresswoman when Clinton was impeached, noted that in the last impeachment, it was the House speaker who lost his seat, not the president.

'People would revolt'

One central player in today's drama doesn't seem to be looking for lessons from the past: Trump.

"It's hard to impeach somebody who hasn't done anything wrong and who's created the greatest economy in the history of our country," the president told Reuters in an Oval Office interview last week. "I'm not concerned, no. I think that the people would revolt if that happened."

Even so, NBC News reported that Trump told friends he was alarmed about the prospect of impeachment.

Gingrich, a Trump ally, said the president hasn't been interested in talking about Clinton's strategy of survival. "He couldn't care less," Gingrich said in an interview. Trump trusts his instincts and has honed his own style. "For 30 years now, Trump has been very successful as a counterpuncher. He has a New Yorker's attitude about fighting" and a willingness to "pound his way" through challenges.

"What he doesn't have is a capacity to be passive," Gingrich said. "Trump believes, probably correctly, he's his own best communicator and if he keeps his base revved up, he will not be convicted, period. He will be president, period."