Washington (CNN) History can be a wise teacher, but it's also crucial to take the right lessons. Confronted with a should-they-or-shouldn't-they proposal on impeachment, Democrats worry that if they fail to learn history's lessons, they are doomed to repeat them.

But while House Speaker Nancy Pelosi seemed to tamp down plans for impeachment during the conference call, some Democratic presidential candidates sharpened their arguments at CNN's town halls Monday night for moving forward with impeachment proceedings.

Polls show most Americans don't favor an impeachment battle and immovable support for Trump among his base, so many Democratic lawmakers are buying into the conventional wisdom that impeachment could consign them to the same fate as 1990s Republicans.

But a longer-term look at the fallout from Clinton's impeachment in 1998 may tell a different story than Democrats now seem to be remembering.

It's true that House Republicans performed poorly in the midterm polls in the middle of Clinton's impeachment drama a nd that the 42nd president left office with unusually high approval ratings.

But less than two years after Clinton escaped with his job from a Senate impeachment trial, Republicans won the presidency after using the outgoing president's morals to underpin their campaign.

The other modern presidential election with an impeachment overhang, in 1976, also saw the incumbent party lose to a candidate -- Democrat Jimmy Carter -- implicitly running against scandal. Two years after Richard Nixon left office before he could be impeached over Watergate, Carter won the White House after capturing the anti-Washington mood by telling Americans, " We just want the truth again."

History offers contradictory examples for Democratic leaders, such as Pelosi, who has her own memories of impeachment as a rising star of the 1990s and held the conference call with her members on Monday to discuss next steps.

Of course, the overriding question should be whether the actions of a President demand impeachment because they meet the constitutional bar of high crimes and misdemeanors, not whether the process could bring partisan advantage.

"There are some decisions that are bigger than politics," Sen. Elizabeth Warren of Massachusetts recently said, invoking loftier motives even as she sought a political payoff by becoming the first Democratic presidential candidate to call for Trump's impeachment after the Mueller report.

Warren consolidated her argument in a CNN town hall meeting in New Hampshire on Monday night.

"There is no political inconvenience exception to the United States Constitution," Warren said. "If any other human being in this country had done what's documented in the Mueller report, they would be arrested and put in jail."

Another Democratic candidate, Sen. Kamala Harris of California, adopted a similar position to Warren at the same town hall event, amid growing differences between 2020 hopefuls and Democratic leaders in the House.

"I believe Congress should take the steps towards impeachment," Harris said.

Another 2020 contender Sen. Bernie Sanders of Vermont called for an "objective" investigation in the House but warned that constant impeachment talk could distract from Democratic priorities like health care, raising the minimum wage and tackling climate change.

No case to answer

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Trump's defenders argue that Mueller's failure to establish conspiracy between the President's 2016 campaign team and Russia and lack of a decision on whether Trump obstructed justice mean that impeachment would be a frivolous and unjustified process. Some are also warning Democrats they would face a backlash if they go ahead.

After Mueller's effort revealed Trump's pattern of lying and use of his presidential power to thwart investigations, few Democrats question whether Trump deserves to be impeached. But the debate is turning not on the question of Trump's guilt but on whether Democrats think impeachment is a smart political idea.

One Democratic argument from before the release of the redacted Mueller report last week is that Democrats would play into Trump's hands by impeaching him. The Senate GOP majority would protect the President from conviction in an impeachment trial and the process would unify Republicans and electrify Trump's 2020 base.

Advocates of this position point to what happened when the Republicans impeached Clinton in 1998. In the subsequent midterm elections, Democrats bucked historic trends and picked up five seats, a shock win that contributed to Republican House Speaker Newt Gingrich losing his job.

The result was seen as a referendum on Republican overreach after Clinton was impeached for committing perjury and obstruction of justice following a scandal arising out of his affair with White House intern Monica Lewinsky. It also suggests to some 21st-century Democrats what can happen when a party puts an attempt to destroy a presidency before issues that voters most care about.

"With President Clinton, the impeachment proceedings became a proxy for the election," Democratic Rep. Stephen Lynch of Massachusetts told CNN's Dana Bash on Monday. "(Clinton's) popularity went up. Some of it was sympathy, some of it was the facts that people saw that impeachment proceeding as a proxy for his worthiness for being elected."

"If the next two years becomes about impeachment instead of about judging the President on his first term. ... I think it may play into President Trump's hands for reelection," he said.

JUST WATCHED Sen Elizabeth Warren calls for House to start impeachment proceedings against Trump Replay More Videos ... MUST WATCH Sen Elizabeth Warren calls for House to start impeachment proceedings against Trump 02:36

Polling may support Lynch's position since the re is no data that suggests the Mueller report is the top issue for voters on either side of the political divide.

Given the polarization of the Trump era, Mueller's conclusions are also unlikely to change the voting preferences of the most committed partisans. Maybe it's not worth risking the votes of anyone left in the shrunken political middle ground with a long impeachment drama.

The evidence of the 2000 election does suggest that there is precedent for draining months of scandal and high-profile congressional investigations to have a detrimental impact on the party holding power.

In the 2000 presidential election, Republican nominee George W. Bush -- who branded himself as an outsider despite his presidential lineage -- repeatedly vowed to restore "honor and dignity to the White House" as he jammed the Democratic nominee -- Vice President Al Gore -- over Clinton's behavior.

The tactic played on voter fatigue of eight years of Clinton scandals, including the impeachment saga, internal White House controversies and allegations of illegal fundraising -- and even the ethics questions that swirled around Gingrich and other Republicans.

But the message's potency lay in its deft, implicit reference to impeachment. Bush used the attack to leave Gore with an unpalatable choice of renouncing the man he hoped to succeed and carrying the can for his improprieties.

"If he's got a problem with what went on in the past, he ought to explain what it is," Bush told reporters in 2000 in a clear reference to the Lewinsky scandal.

In the end, Gore was never able to find a way to benefit from Clinton's popularity and to insulate himself from lingering questions about his morality and Bush won a disputed election that was eventually settled by the Supreme Court.

Impeaching Clinton did not hurt the GOP in subsequent elections either, since the party outperformed in the 2002 midterms and retained the presidency in 2004, though the dynamics of those two elections were largely shaped by the trauma of 9/11.

One difference in the current scenario is that the scandal-tainted President is expected to be on the ballot himself in 2020 -- and Trump has shown a staggering capacity to sidestep even the most damaging political scandals.

While red state senators would love to save Trump in a Senate trial, such a vote would be politically damaging for Republican senators up for re-election in presidential swing states

Impeachment may not be 'worth it'

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But many top Democrats seem to have made up their minds on impeachment even before the redacted Mueller report was released last Thursday.

While they want to avoid the worst risks of an impeachment saga, Democrats also want to reap the benefits of Mueller's unflattering account of Trump's behavior.

For now, they are pursuing a hybrid approach by holding a series of high-profile hearings with eye-catching witnesses and probing the President's alleged obstruction.

In many ways this is going through the motions of impeachment without the end result, in an attempt to frame a case to voters that Trump is unfit to serve a second term.

"While our views range from proceeding to investigate the findings of the Mueller report or proceeding directly to impeachment, we all firmly agree that we should proceed down a path of finding the truth," Pelosi wrote in a letter to colleagues on Monday.

"It is also important to know that the facts regarding holding the President accountable can be gained outside of impeachment hearings," she added.

Pelosi doesn't have the luxury of waiting for history's verdict as she plots the Democratic strategy over the next 18 months until Election Day.

If she chooses to avoid impeachment and Democrats put a new president in the White House, she will be vindicated. But if Trump wins reelection despite the choking cloud of scandal around his White House, Democrats may question why they didn't try to mortally wound him politically when they had the chance.