McConnell's statement, made on the Senate floor, comes shortly before the Senate begins what is expected to be an hours-long debate over the rules governing the impeachment proceedings.

McConnell called the rules fight an "entrance exam" that will determine if the Senate can "put fairness, evenhandedness and historical precedent ahead of partisan passions."

"The organizing resolution already has the support of the majority of the Senate. That's because it sets up a structure that is fair, evenhanded and tracks closely with past precedents that were established unanimously," McConnell said.

Democrats have taken issue with two provisions, in particular, in the rules resolution: While it gives both House managers and Trump's legal team 24 hours each to present their case, it breaks with the 1999 trial of President Clinton by requiring them to use that time within two days.

It also does not admit House evidence into the trial record until after the Senate votes on whether to call witnesses or admit documents. Leadership is expected to call that vote before opening arguments and questions from senators.

Democrats are pledging to force a slew of votes on calling witnesses, compelling documents and making changes to the rules.

McConnell warned that the Senate will remain in session, even if it takes hours, until the rules are adopted.

After opening arguments, which should conclude on Saturday, senators will have 16 hours to ask questions in writing though Chief Justice John Roberts, who is presiding over the trial.

McConnell also took a shot at House Democrats Tuesday, saying his rules "will draw a sharp contrast with the unfair and precedent-breaking inquiry" in the House.

"The House broke with fairness by cutting President Trump's counsel out of their inquiry to an unprecedented degree," McConnell said.

The White House previously declined to take part in the House process.