Sen. Chris Van Hollen of Maryland has announced a challenge to Chuck Schumer for Senate majority leader, opening a contest over who will guide the Democratic caucus when it takes control of the Senate in January. The leadership vote is expected in early December, and will be a closed-door, secret-ballot election.

What Van Hollen and Schumer have said

Van Hollen said the election results showed voters wanted a change in leadership and described his candidacy as a bid to meet that demand. Schumer responded that he welcomes discussion about the caucus’s future and says he has enough support to continue leading it.

The two senators are entering the contest with different arguments about the party’s direction. Van Hollen has criticized Schumer over his handling of the Trump administration and the influence of special interests. Schumer’s allies point to his role in recruiting candidates and helping Democrats win a 55-seat majority, with the final count still dependent on Alaska.

A rare leadership contest before Democrats take the majority

The Associated Press reported that the coming vote would be the first contested election for Senate Democratic leader in decades. Sen. Bernie Sanders and Sen.-elect Abdul El-Sayed have backed Van Hollen, while several other members have publicly supported Schumer or have not said how they will vote. The result will determine who sets the caucus’s priorities and negotiates the party’s agenda as the new Congress begins.

Schumer has begun discussions with senators about a first-100-days plan that could include health care and tariff legislation, according to AP. Van Hollen’s challenge puts the focus on whether members want continuity after the party’s midterm gains or a change in leadership before those policy choices are made.

For context on the Senate’s upcoming majority, see what the incoming Democratic majority could mean for Trump’s judicial nominees.

Sources: Associated Press; CBS News.