A Democratic senator is openly challenging Chuck Schumer for the top Senate leadership job, a sign that last week's big election wins have emboldened the party's left flank to demand new leadership.

• Senator Chris Van Hollen announced he's running against Schumer for Senate Democratic leader, with the vote set for December 1st.
• Schumer says he already has the votes and isn't worried, but the vote is secret, so public pledges may not hold.
• Van Hollen claims 10 senators have privately committed to him versus 18 publicly backing Schumer, leaving the outcome unclear with new incoming senators who owe Schumer no loyalty.
• Schumer is deeply unpopular nationally, even less popular than Trump, and critics say he's out of step with voters on the Iran conflict, primary elections, and campaign finance.
• Even if Van Hollen loses, the challenge is seen as a way to pressure Schumer and the broader Democratic establishment to be more responsive to voters rather than donors.

Outlook: The vote is too close to call given the secret ballot, but pressure on Schumer is expected to keep building regardless of the outcome, with bigger fights over the Supreme Court and the filibuster looming.