Senate Majority Leader Chuck Schumer and Mitch McConnell's inability to quickly strike a deal on a power-sharing agreement in the new 50-50 Congress is slowing down everything from the confirmation of President Biden's nominees to Donald Trump's impeachment trial.

Why it matters: Whatever final stance Schumer takes on the stalemate, which largely comes down to Democrats wanting to use the legislative filibuster as leverage over Republicans, will be a signal of the level of hardball we should expect Democrats to play with Republicans in the new Senate.

The holdups: Everything being done in the Senate right now is operating on unanimous consent agreements, which can only work for so long and won't fly when Democrats try to pass serious legislation, like a forthcoming pandemic relief bill.

• The committee ratios are currently in favor of Republicans, and Democrats need the power sharing accord to sort out the new committee make-ups and chairmen.
• House Speaker Nancy Pelosi says she is waiting to send the article of impeachment against Trump to the Senate until the organizing resolution is completed (a similar posture she insisted on in Trump's first impeachment trial).

State of play: McConnell and the GOP conference want an upfront commitment from Democrats that they will not try to eliminate the 60-vote legislative threshold and hold it over their heads during negotiations over the next two-plus years.

• Many Senate Republicans have begun circulating a bipartisan letter from 2017 signed by 61 senators, including then-Senator Kamala Harris, who supported upholding the filibuster when Republicans ruled both chambers of Congress and the White House.

What they're saying: “I think at the moment, it’s a little bit stalled out, but I hope they can get back on track," Senate Republican Whip John Thune (S.D.) said of the status of the sharing agreement. "Obviously the big issue was the legislative filibuster."

• Centrist Sen. Joe Manchin (D-W.V.): “Chuck has the right to do what he’s doing. He has the right to use [the filibuster] to leverage in whatever he wants to do. .... They’re not going to grind this place to a halt."
• Sen. John Barrasso (R-Wyo.): “There was a letter that Sens. Collins and Coons generated [in] 2017 when, at the time, President Trump was calling for an elimination of the filibuster pretty forcefully ... senators said ‘no, we should not change that, we should continue with the legislative filibuster.’"