On the night House Democrats made history their counterparts in the Senate were watching, including New York Senator Chuck Schumer.

Being the top Democrat in the Senate, Schumer is playing a key role in how a potential Senate trial will take place.

“The Senate begins this new session of Congress preparing to do something that has happened only twice, twice before in American History,” Schumer said.

As the minority leader, Schumer’s strategy has largely relied on keeping Democrats unified on key issues, from immigration to health care.

With the exception of one or two swing-state Democrats, the party appears mostly on the same page, in contrast to Senate Republicans who are sometimes at odds with the President and his unconventional style of governing.

Schumer’s main demands for an impeachment trial include compelling the White House to produce documents it blocked from House investigators, as well as allowing key witnesses, who defied House subpoenas - to testify.

“Since Congress recessed for the holidays there have been several, several, events, that have significantly bolstered my argument for four specific witnesses and specific categories of documents,” he said.

While the Democrats in the House ran the show, it’s opposite in the Senate.

The upper chamber split 53 Republicans to 47 Democrats. Fifty-one votes, a simple majority, is needed to pass any ground rules, which means Schumer needs four moderate Republicans to defect, and for the Democrats to show total unity.

“The rules of this will be determined by a majority of Senators in this chamber, not by the Republican leader, alone,” he said.

Schumer is taking a gamble with the strategy, as the president is still popular in some blue states.

Republicans could also call witnesses if the rules allow, which means Hunter Biden, the son of former Vice President Joe Biden, could also make an appearance.

Overseen by Chief Justice John Roberts, the trial itself is also expected to make the case more to the voting public than to senators, as 67 of them must vote to convict and remove Trump from office, a very unlikely scenario.

For the moment Democrats – led by Schumer – appear to be continuing their public pressure as the Senate gets back into Washington. But this time, it's now officially in an election year.