A 50-50 Senate: Democrats in power but not control

If Joe Biden wins the presidency, he could end up with a 50-50 Senate split — an outcome giving Democrats formal control of the upper chamber but also empowering individual senators greatly and requiring a procedural feat to abolish the 60-vote filibuster rule.

Why it matters: A President Biden would need a Senate majority to make good on many of his campaign promises.

That would happen only if Democrats make the bank shot of winning two likely Senate runoff races in Georgia in early January, climbing from the minority to a 50-50 split in the next Congress — with a Vice President Kamala Harris breaking tie votes.

• That power, enshrined in the Constitution, would allow Sen. Chuck Schumer to act as majority leader, but Schumer would have to broker a deal with Sen. Mitch McConnell about everything from floor procedures to committee seats.
• Democrats would still need to win 50 votes for any major institutional rule changes or big spending packages, and they'd need buy-in from potential rogue Democrats like Joe Manchin and Kyrsten Sinema.
• Outlying Republicans such as Mitt Romney, Susan Collins and Lisa Murkowski could also hold leverage over their own party on narrow votes.

Go deeper: In her role as the Senate's tie-breaker, Harris would be able to give Democrats the 51 votes they'd need to eliminate the filibuster for legislation, said Molly Reynolds of the Brookings Institution.

• But that's only if they could get the votes of all 50 Senate Democrats, including moderates like Manchin and Sinema.
• The Biden-Harris team hasn't taken an explicit position on the abolishing the filibuster and Biden — a 36-year veteran of the chamber — has voiced his support for keeping it.
• “They can try it but it’s very unlikely. In fact, I think it’s almost ridiculous to think about it,” says former Senate historian Donald A. Ritchie.

Flashback: The once-sacrosanct filibuster already has been weakened. Senate Democrats triggered the so-called "nuclear option" in November 2013 by voting to drop the number of votes from 60 to 51 to confirm Cabinet secretaries and most federal judges, though not Supreme Court justices.

• When Republicans clawed back the majority after the 2016 election, McConnell eliminated the 60-vote requirement for the Supreme Court as well, allowing Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett to join the high court.
• In January, Democrats could respond by eliminating the 60-vote requirement for most legislation — but only if they can get every member of their caucus on board, as well as Harris.

Don’t forget: Vice President Dick Cheney broke ties in a 50-50 Senate after the tumultuous 2000 election where George W. Bush won the presidency over Al Gore.

What we're hearing: To pass some spending and tax legislation, Democrats can use the "budget reconciliation" process, which doesn't require a filibuster-proof 60 votes.

• But just where and how "budget reconciliation" rule would apply will be subject to negotiation between Schumer and McConnell.
• Those two Senate bulls would also have to figure out committee assignments, but they'd likely follow the 2001 compromise, when Sens. Tom Daschle and Trent Lott divided the committees evenly, with the vice-president's party assuming the chairmanship.

Be smart: Harris would have to be on constant call for Senate business — but the Democrats would find that preferable to having McConnell and the Republicans control the chamber.