What is the history of the 50-50 Senate?

In baseball, the saying "the tie goes to the runner" means that if two players are tied for a record, the one who has played more games will be considered the better player.

If only it were that simple in the United States Senate.

The 119th Congress, beginning in January, has a high probability of being evenly divided between the Democrats and Republicans with a 50-50 Senate.

The Senate map in play next week is expected to favor Republicans, with Democrats currently holding a slim 51-49 edge. However, there are four independent senators who "caucus" with the Democrats, giving them operational control.

The belief that the party controlling the vice presidency automatically gains control of the Senate is not entirely accurate. While the vice president serves as the President of the Senate and has the power to break ties, Senate control is not automatically granted. There have been two Senate ties in recent history, in 2001 and 2021-2023. Understanding what happened in these instances can help explain why awarding Senate control to the party of the vice presidency is not a given. Additionally, these circumstances could contribute to the complexity of determining which party might control the Senate in 2025.

Let’s first rewind.

In 1881, the Senate had a tie, which was caused by infighting and resignations of senators. Similarly, there was a tie in 1954, and there were multiple switches in the majority/minority of senators between 1953-1955. This was due to the death of nine senators over a short period of time.

In the early 21st Century, there were two ties. However, one party or the other usually had more members than the other side. Despite this, there was no "Majority Leader" or "Minority Leader" until the early 20th Century. Senators viewed the institution as a group of equals, so there was no need to designate someone as "in charge." This changed approximately 100 years ago, leading to the contemporary Senate.

In late 2000, the Senate ended a decades-long tie at 50-50 with Sen. Maria Cantwell, D-Wash., winning the final race called over late Sen. Slade Gorton, R-Wash., in December. The year 2000 also saw the Florida election dispute over the presidency between President George W. Bush and Vice President Al Gore. Trent Lott, R-Miss., and Tom Daschle, D-S.D., brokered a power-sharing arrangement after the 50-50 split. Lott became the majority leader, while Daschle gained some floor powers not typically granted to the Minority Leader. Republicans would chair Senate committees, but committee membership by Democrats was equal to that of the GOP.

The pact stipulated that if either party gained a formal majority in the Senate during the 107th Congress, the deal would be invalidated and the party with the majority would truly control the Senate.

The agreement was reached due to the level of comity between Lott and Daschle, and all 100 senators agreed to the power sharing arrangement. The reason for everyone's support was that Lott and Daschle earned the confidence of their members, and Republicans knew that Democrats would block anything if they weren't granted a sufficient voice. Meanwhile, Democrats agreed to the pact because the alternative meant they were relegated to the minority, but with an asterisk.

Lott's slender majority was quickly lost when Sen. Jeffords, I-Vt., left the GOP and became an independent, aligning with the Democrats. This move immediately made Daschle the new Majority Leader.

The control of the Senate for the 117th Congress was not determined until early 2021. This was when Sen. Raphael Warnock, D-Ga., defeated Sen. Kelly Loeffler, R-Ga., resulting in a 50-50 tie. President Biden won the presidency. Republicans were concerned about being shut out, while Democrats worried about the same fate in 2001. Senate Minority Leader Mitch McConnell, R-Ky., insisted on the same power-sharing arrangement as Lott and Daschle two decades ago. As Vice President, Kamala Harris would serve as the majority party, with Chuck Schumer, D-N.Y., leading the Senate. However, the GOP would still have some power in the minority due to the 2001 deal.

So what happens if there’s a tie in 2025?

The Senate is steeped in custom and tradition. If there's a 50-50 deadlock, there's a good chance a "Vice President Tim Walz" means Democrats are in charge. The same for the GOP if there's a "Vice President JD Vance." However, we're operating in a different political atmosphere these days. While the power-sharing arrangements of 2001 and 2021 both emerged after disputed presidential elections, there was an interest in both instances to calm the waters in both of those episodes. But this time around, who knows?

Could the possibility of an independent senator not caucusing with either party complicate the race between Dan Osborn and Deb Fischer in Nebraska?

After the election, there may be restive senators, and McConnell is stepping down as leader. The candidates to succeed him are Senate Minority Whip John Thune, R-S.D., former Senate Majority Whip John Cornyn, R-Tex., and Sen. Rick Scott, R-Fla. It's possible other senators could also be in the running.

The Republican leader may be weakened by Sen. Mike Lee, R-Utah, urging GOP leadership candidates to change internal conference rules. It's unclear if there will be a desire for bipartisanship and goodwill in the new Congress if there is a Senate tie.

If there is disagreement about who won the presidency between Harris and former President Trump, it could affect whether senators would award the "majority" to one side or the other if it is unclear who is Vice President, either Walz or Vance.

The Vice President has the power to break ties in the Senate, but they are not required to vote in such situations. If there is a 50-50 vote on a bill or amendment, a tie loses by rule. Therefore, if a vote is tied, the Vice President won't vote if the administration or party wants the issue to go down to defeat. There's no reason to cast a "nay" vote to pile on with the loss.

The Vice President votes "aye" in the event of a tie vote, allowing the issue to pass with a 51-50 vote, even if the President and Vice President disagree on the outcome.

If the vote is 49 yeas to 50 nays, the Vice President cannot vote as it is not a tie. Therefore, the Vice President does not have a vote to tip the balance to 50-50.

Although the vice president has traditionally had the authority to determine which party will control the Senate, the vice president's power is quite restricted.

The possibility of a divided Senate in 2025, amid a volatile political climate, could make it challenging to determine which party controls the Senate.