Maryland Sen. Chris Van Hollen said Thursday that he will run for Senate majority leader, setting up a challenge to longtime Democratic leader Chuck Schumer when the party holds its caucus elections next month.

Van Hollen cast his bid as a response to the midterm election results, saying voters had called for change not only from “Donald Trump’s disastrous policies” but also from a “status quo that isn’t working for working people.”

“It’s now on us to meet this moment, and to do that we need new leadership,” Van Hollen said in a statement. “This is not about any one person — it’s about answering the call of the American people.”

The announcement is a setback for Schumer, who remains favored to become leader but had previously predicted that he would face no challenger. Van Hollen’s entry ensures that Democrats will have a choice when they select their leadership next month.

A veteran of Democratic politics, Van Hollen, 67, has held public office continuously since 1991. He served 14 years in the House before winning election to the Senate in 2016.

In recent years, the Maryland senator has become a more outspoken critic of his party’s leadership, particularly its approach to Trump and the U.S.-Israel relationship. His campaign for majority leader brings those differences into the contest for the party’s top Senate position.

Van Hollen’s statement framed the race around the party’s response to voters and the need for a different approach to issues affecting working people. While he did not single out Schumer in the statement, his call for new leadership directly challenges the New York senator’s continued hold on the post.

Democratic senators are scheduled to decide the leadership contest in their caucus elections next month.