Trump-Clinton, Clinton-Trump.

The surnames are bound by the contentious presidential contest of 2016 between Donald Trump and Hillary Clinton, the effects of which continue to reverberate in terms of policy and the composition of the Supreme Court.

Now the names of Trump and Bill Clinton are likely to be linked by the dubious distinction of being the second and third presidents, respectively, to be impeached by the House of Representatives.The impeachment process has only seriously been initiated on four occasions. Here are the ways in which the Clinton and Trump scenarios compare and contrast:

Clinton was impeached by the House on Dec. 19, 1998. The full House vote on articles of impeachment against Trump could fall exactly 21 years later.

The Clinton impeachment trial began in the Senate on Jan. 7, 1999. Senate majority leader Mitch McConnell has said if the House recommends the impeachment of Trump, the trial process will begin as soon as legislators return in early January.U.S. Senate majority leader Mitch McConnell says no decision has been made about what kind of trial the Senate will have if the House votes, as expected, to impeach the president. (Tom Brenner/Reuters)

Amid the heated environment, Clinton had to give a state of the union address on Jan. 19, 1999, a speech that gave no hint of the impeachment drama.

Trump's next state of the union could also occur in that kind of heightened circumstance, though an exact date has yet to be determined. Given his mercurial nature, it is debatable whether he'd be able to compartmentalize as Clinton did.

Republicans have a majority in the Senate, as in 1999. There are 16 Senate holdovers who rendered a verdict on Clinton, including Republicans McConnell and Chuck Grassley and Democrats Chuck Schumer and Dianne Feinstein.

There are also a few former House members during the Clinton proceedings who are now senators, none more prominent than South Carolina's Lindsey Graham, an outspoken defender of Trump's presidency.

Lindsey Graham was a member of the House judiciary committee and one of the so-called managers who presented the case for impeaching Bill Clinton. Now in the Senate, Graham has panned the efforts by Democrats to impeach Trump. (Tim Sloan/AFP via Getty Images)

"I'm not trying to pretend to be a fair juror here," Graham, a former military and civilian prosecutor, said last week of the likely Senate trial.

"I will do everything I can to make it die quickly."

In 1999, Graham was one of the so-called House managers presenting the case for Clinton's impeachment in the Senate.

"For God sakes, figure out what kind of person we have here in the White House," Graham said in his impassioned closing statement. "For God sakes spend some time trying to fulfil your constitutional duty so that we can get it right, not just for our political moment, but for the future of this nation."

Expect much jockeying for position ahead of and during the Senate trial, as happened in 1999 — including motions to dismiss the case and the request for witnesses to give testimony. Republicans then managed to secure a deposition from former White House intern Monica Lewinsky, though from a remote location and not inside the chamber.

Schumer, now minority leader in the Senate for the Democrats, on Monday formally requested testimony at a Senate trial of four individuals who did not testify in the House to ensure a "full and fair trial," a list that includes former Trump national security adviser John Bolton and White House chief of staff Mick Mulvaney.

The two sides will also have to come to an agreement on the length of testimony and presentations. In the Clinton trial, each side would get 24 hours to present its case. Two days were allotted for senators to ask questions to the House managers and the president's surrogates.

The road to impeachment was winding in both cases.

An investigation that had started five years earlier with a look into Bill and Hillary Clinton's real estate holdings in Arkansas was eventually overtaken by Clinton's statements under oath in a civil suit involving Paula Jones — who alleged Clinton had sexually harassed her — concerning his relationship with Lewinsky, who had admitted a sexual relationship with Clinton.

Kenneth Starr, seen testifying on Nov. 19, 1998, in the House, was not the original independent counsel investigating the Clintons. His appointment was one of many events to occur over a winding, five-year path to impeachment. (Doug Mills/The Associated Press)

With Trump, there had been a reasonable expectation that if he faced an impeachment trial over obstruction of justice and other "high crimes and misdemeanours," it would be concerning Russia. From the very first day of his presidency, questions about contacts between members of his 2016 campaign and Russian officials swirled, and special counsel Robert Mueller's investigation helped lead to criminal charges for several men in Trump's orbit.

But by the time Democrats emerged from August recess, Mueller's congressional testimony on July 24 took a backseat. It was emerging that a whistleblower had sounded the alarm about Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky.  

The substance couldn't be more different, even if both men faced articles related to abuse of office and obstruction.

Democrats say Trump clearly leveraged the power of his office to pressure Ukraine, an ally engaged in a conflict with Russia, to announce a pair of investigations he found desirable, including one of potential 2020 presidential rival Joe Biden. One way Trump applied pressure, they argue, was by withholding nearly $400 million in military aid for Ukraine.

Therefore, Democrats claim, the behaviour has implications for the upcoming election and must be addressed immediately.

Democrats say Trump, right, abused his power in a July 25 phone call when he asked Ukrainian President Volodymyr Zelensky, centre, for a favour in investigating Democratic presidential candidate Joe Biden. (Bastiann Slabbers, Ludovic Marin, Yuri Gripas/Reuters)

Clinton's actions weren't considered to have implications for the nation's security, though Republicans tried to argue that a four-day bombing campaign in Iraq in December 1998 was designed to distract from the president's troubles.

Given the unique nature of the Clinton allegations, we're unlikely to see a moment in the coming weeks analogous to Republican Speaker-in-waiting Robert Livingston resigning from the House floor due to his own extramarital affairs in a bid to up the pressure on Clinton.

It may be the same time of year, but the political cycle is much different.

The Clinton impeachment took place weeks after a midterm election. Sixteen Senate seats had just been contested, meaning those winners weren't up for re-election until 2004. The rest, as well as the House members, still had some 20 months before facing voters again.

A Trump impeachment trial would be taking place 10 months before the next election, with some 470 seats in Congress overall to be contested in November. While the large majority of seats are considered by prognosticators as not seriously in play regardless of events, it's conceivable the specific impeachment votes of a number of legislators could weigh on the minds of voters in their respective districts.

The timing also differs from modern impeachment processes in that Richard Nixon and Bill Clinton were in their second and final terms, while Trump is seeking re-election.

"They aren't listening to us," a 54-year-old factory worker who voted twice for Clinton told The Associated Press in late 1998. "Republicans have been out to get Clinton since he was first elected."

A rancher, meanwhile, told the same bureau, "Some way or other, he's gotta pay for his lyin'."

The reactions may sound familiar, but the overall complexion of public reaction differs.

Trump, left, shares a laugh with President Bill Clinton on Sept. 8, 2000, at an event in New York. Once friendly acquaintances, they could be among the three presidents, in addition to Andrew Johnson, to be impeached by the House. (William J. Clinton Presidential Library via Reuters)

Support for Clinton's impeachment usually hovered in the mid-30s, percentage-wise, and his job approval rating actually jumped by 13 percentage points to over 70 per cent in one poll taken immediately after the House impeachment.

Trump's approval ratings have generally been within the same margin of eight percentage points from the high 30s to mid-40s throughout his presidency.

The manner in which people receive and process news has changed drastically — according to the Pew Research Center, 41 per cent of U.S. adults used the internet in 1998, versus over 90 per cent today. Social media and its ability to provide instantaneous opinion and coverage were years away, and Fox News was not as dominant in shaping conservative opinion.

Are these factors and others ossifying public opinion? A poll released Sunday by Trump-friendly Fox found 41 per cent surveyed opposed impeachment altogether, the exact same figure as a poll Fox commissioned in October.

Before he died, Republican Henry Hyde told author Ken Gormley for the 2010 book, The Death of American Virtue: Clinton Vs. Starr, that selecting 13 House managers — all white men — to present the case in the Senate prolonged the proceedings and led to repetition.

Impeachment is the political process of removing from office certain elected or public officials accused of wrongdoing. The process is more difficult than you might think. 2:01

 

It can reasonably be expected that the Democrats will have a much smaller but more diverse group. Reports have emerged that they would like to draft Justin Amash of Michigan as one of the managers in a bid to look more bipartisan. Amash declared himself Independent in July after his not-infrequent criticisms of Trump fell on deaf ears within the Republican Party.

Along with rumblings in media reports that the White House could present a limited defence of Trump, it is among the reasons to suspect a Senate trial will not last 37 days as in 1999.

The details have yet to be worked out but the expectation is that Trump will be impeached in the House and acquitted in the Senate. The level of pretrial suspense is actually comparable with the Clinton case.

In December 1998, ardent Clinton critic Orrin Hatch publicly doubted his Republican Party could meet the two-thirds threshold to convict in the Senate.

There will be media attention this week focusing on the House Democrats who vote against the articles of impeachment, but that happened in the Republican-led House of 1998, too. Twenty-eight Republicans balked at Article 2, and 81 decided Article 4 was a reach.

The results in the House for the articles of impeachment against Clinton were:

The Senate on Feb. 12, 1999, acquitted Clinton 55-45 on perjury and 50-50 on obstruction of justice.