To prepare, Republicans and Democrats are studying up.
Republican Sen. Mitt Romney of Utah, an occasional critic of the President who has been careful not to tip his hand ahead of a Senate impeachment trial, has read over the Federalist Papers in an effort to get a sense of how the Founding Fathers viewed impeachment.
“We’re all trying to get up to speed because this doesn’t happen very often,” Cornyn told CNN, adding that the book “brought home how serious and really unique impeachment is.”
“In a country where the people are supposed to be in charge, the idea of having 535 members of Congress essentially reverse a decision made at the ballot box is a pretty serious responsibility,” Cornyn said.
‘It’s somewhat unpredictable’
As senators prepare for a historic event, there’s a distinct sense on Capitol Hill that nobody knows quite what to expect from an impeachment trial.
For one thing, there’s not that much past precedent.
Only three presidents have been impeached by the House: Johnson, Clinton and now Trump. Johnson and Clinton both faced a Senate trial, but were acquitted and not removed from office. Former President Richard Nixon faced an impeachment inquiry, but resigned before the House could vote to impeach.
There’s another reason for a sense of uncertainty.
That’s because the way a Senate trial will ultimately unfold will depend on what senators can agree to. One way that might happen is if Senate Majority Leader Mitch McConnell and Senate Democratic leader Chuck Schumer are able to negotiate an agreement that sets parameters for the proceeding. If not, Republicans may be able to dictate procedure with just 51 votes.
If neither scenario plays out, then after the House presents its case for impeachment and the President’s lawyers outline their defense, each issue that arises could be dealt with as essentially a “jump ball” in the words of McConnell with senators taking votes on motions put forward.
“It’s somewhat unpredictable,” said Democratic Sen. Mazie Hirono of Hawaii. “The rules and how we are going to proceed will need to be negotiated.”
The House also took its final vote of the year without appointing impeachment managers or sending articles of impeachment to the Senate, suggesting that Democrats won’t take the steps needed to start the trial until January.
‘I’m reading quite a bit’
To get a sense of what’s to come, senators are reading books on impeachment, studying transcripts of past impeachment trials and watching videos of past proceedings.
They’re pouring over Senate rules to familiarize themselves with what to expect. They’re asking aides to prepare briefing documents and compile articles to use as reference material and they’re turning to colleagues who served in Congress during past impeachments for guidance.
“I’m reading quite a bit of material,” Republican Sen. Ted Cruz of Texas told CNN, adding, “Rules, historical precedents.”
Blumenthal said that he’s reading “anything and everything” he can get his hands on, including past impeachment transcripts.
In addition to reading the Federalist Papers, Romney has been reviewing prior presidential impeachments as well as impeachments involving federal judges, and is working with staff and legal counsel to go over the process for a Senate trial.
Cornyn told CNN that he’s also studying the resolution negotiated between then-Senate Majority leader Trent Lott, a Mississippi Republican, and Democratic Minority Leader Tom Daschle of South Dakota, during the Clinton impeachment trial.
There have also been closed-door briefings on the subject of impeachment during routine caucus meetings.
“We’re beginning to have a series of briefings in our caucuses,” Democratic Sen. Tom Carper of Delaware said, adding that recent briefings have “focused largely on looking back at earlier impeachments” in Congress.
Democratic Sen. Tammy Baldwin of Wisconsin told CNN that senators are sharing recommendations of books they have found helpful as they prepare for a trial.
“There were just book recommendations made in our caucus meeting for our holiday reading,” she said.
“I’m going to have a lot of reading to do,” Casey said, adding that he is also reviewing the House Intelligence Committee’s report on its impeachment investigation into the Ukraine scandal and familiarizing himself with Senate rules and procedures related to impeachment.
‘I’ve done it once before, I’m ready to go’
Some senators plan to draw on the institutional knowledge that exists in the upper chamber by turning to lawmakers and aides who were around for past impeachment proceedings to get a sense of what’s to come.
“We have some staff who were involved in the impeachment proceedings of President Clinton. We have members who were involved and staff who were involved,” Carper said, “I’m talking to people who were there. What was it like? What should we know?”
And some lawmakers feel prepared for what’s to come based on past experience — or at least as prepared as they can be.
Those Republican lawmakers who served as managers and still hold seats in Congress are: Rep. Steve Chabot of Ohio, Rep. Jim Sensenbrenner of Wisconsin and Sen. Lindsey Graham of South Carolina, who was a representative of the state’s third congressional district at the time of the Clinton impeachment.
Asked what he’s doing to prepare for a Senate trial this time around, Graham told CNN, “I’ve done it once before, I’m ready to go.”
“I’m ready to listen, that’s what our job is, to listen,” Graham said. “Instead of talking, I’ll be listening. Last time, I was talking.”
CNN’s Ted Barrett contributed to this report.