Major challenger to Biden for Democratic nomination?

This market will resolve to “Yes” if any major candidate announces they are challenging Joe Biden for the Democratic nomination for President of the United States between June 4, 2024, and the moment the Democratic nominee is announced. A major candidate is defined as any current or former Senator, Governor, House member (congressman), Cabinet member, or former President/First Lady. Otherwise, this market will resolve to "No." This market will resolve to "No" if Biden officially wins the Democratic Nomination. If Biden drops out before he wins the Democratic Nomination this market will resolve to "Yes". The resolution source will be a consensus of credible reporting.