The topic of impeachment is back and hotter than ever in Washington. But is it back by popular demand? Will the issue simmer into the fall, or will the heat dissipate in the days ahead?

More Democrats than ever — a majority — now favor opening formal proceedings to remove President Trump from office. More joined the chorus over the weekend after reports suggested Trump pressured an ally to support a certain line of attack on Democratic presidential candidate Joe Biden.

But the fever for impeachment has yet to be felt by much of the public at large.

Polling over the first 30 months of Trump's tenure has occasionally shown his approval ratings fall measurably, as they did after the Charlottesville white supremacy march in 2017 and during the government shutdown earlier this year.

In the wake of Robert Mueller's spring report on Russian interference in the 2016 campaign, some polls even showed support for impeachment rising through the 40s or touching 50%. But other polls, including those that did not reference the Mueller report, found support for impeachment proceedings still well under 40%.

After that, as in previous instances, the moment faded and other stories intruded, and impeachment support subsided.

The truth is — impeachment has almost never been popular. It tends to pump up the partisans in either party but has far less allure for the less politically inclined. Independent voters, it should be noted, have been especially slow to take up the impeachment cry.

It may be aversion to the disruption or dread of the all-consuming nature of the process that devours the congressional agenda and relentlessly dominates the news media. Surely, those are among the memories that linger from the impeachment of President Bill Clinton two decades ago. The Clinton impeachment in December 1998 was never supported by anything close to a majority in the Gallup Poll. A year later, it was more popular and supported by 50%.

In the month he was impeached by the House of Representatives, only 30% of Americans supported removing him from office. Remarkably, in the same poll, nearly two-thirds said they thought Clinton was guilty of the charges involved. The following month, a Republican Senate could not muster the needed two-thirds vote, or even a simple majority, to convict Clinton on either of the articles of impeachment backed by the House.

From time to time, members of the House have since proposed impeaching Clinton's successors George W. Bush and Barack Obama. (Any individual member can go to the floor and do this.) But that came to nothing in both cases. The lesson both parties clearly had taken away from the Clinton case was that the public is cool at best to the whole business.

House Speaker Nancy Pelosi has been adamant in her resistance to impeachment proceedings that have neither bipartisan backing nor broad public support. She had already served a decade of her House career at the time of Clinton's impeachment and acquittal, and she saw how his approval ratings actually rose at that time and through his remaining time in office.

That is clearly not a scenario she would wish to reprise in the next 14 months. But Pelosi was also around for that other impeachment process of the 20^th century, the one involving Richard Nixon. Though not yet a candidate for office, Pelosi was a California mom in her early 30s and active in Democratic politics. Her father had been a congressman and the mayor of Baltimore.

She surely remembers how difficult it had been to sell the public on the case against Nixon, a case so overwhelming by the summer of 1974 that he chose to resign in the face of certain impeachment (with senators from his own party telling him he had to go). Yet, even as Nixon's Washington power base eroded and then collapsed, the public accepted the change only grudgingly.

In a 2014 Pew Research Center study, the center's director and pollster Andrew Kohut noted how long the public had resisted Nixon's impeachment — even as his approval rating declined to historic lows. Even after a long summer of televised Senate hearings in 1973 began the slide in his approval, Gallup found only about 1 in 4 Americans thought Nixon should go.

Even after Nixon fired the special prosecutor, attorney general and deputy attorney general in "the Saturday Night Massacre" that fall, the Gallup percentage for removal went up only 9 percentage points and remained below 40%.

That figure would drift upward through the winter and spring of 1974, a time when it moved in a range similar to the current impeachment numbers for President Trump.

"Only in early August, following the House Judiciary Committee's recommendation that Nixon be impeached and the Supreme Court's decision that he surrender his audio tapes, did a clear majority — 57% — come to the view that the president should be removed from office," Kohut wrote.

But the actual trauma of these impeachment episodes would not be the full story for politicians of Pelosi's generation. They have lived through nearly half a century of subsequent political hurly-burly, witnessing how the backlash to impeachment has colored American politics since.

The Nixon ouster may have seemed a resounding end to that scandal, but it may also have set in motion some of the political forces that have roiled American politics since.

Rick Perlstein is a historian and journalist whose books include Nixonland: The Rise of a President and the Fracturing of America. He has argued that the takedown of Nixon (who had won 49 states in 1972) was traumatic for much of the nation, but in different ways.

In an interview published last month in Mother Jones, Perlstein argues that for "a more sizable portion of the population than was apparent at the time," Nixon's departure engendered deep resentment, spawning much of the energy and tactics seen on the right in the decades since — including in the rise of Trump.

"It felt somehow the liberals were kind of putting one over on the rest of the nation and reversing the results of the 1972 election," he wrote. "In retrospect, the kind of things they were saying then — about this liberal coup to unseat a popular president — sound a lot like what you hear on Fox News now."

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