Context:

I believe House and Senate Democrats, directly elected by voters from across the country, must hold an immediate vote of confidence and share the results directly with Mr. Biden. It can be done by secret ballot, as fear of political retribution still prevents many members from speaking publicly. But a poll of elected Democrats whose electoral fates are closely tied to the president is far superior to one of unelected members of the Democratic National Committee.

If “confidence” wins, we must immediately and aggressively mobilize behind Mr. Biden and redouble efforts to secure a majority in at least one chamber of Congress. But if “no confidence” is the consensus, the president must end his candidacy.

If it is reported that a congressional vote of no confidence occurs which includes at least 80% of House/Senate dems, this market resolves to the reported result of that vote.

If a vote does happen, Biden "wins" the vote if it is reported that he won by whatever threshold the democrats set before the vote. This would most likely be a simple majority, as Dean Philips proposes.

Biden "loses" the confidence vote if it is reported that he did not meet this threshold.

If we do not get clear reports on the outcome of the vote, this market resolves to "Vote happens, but outcome is unclear".

If there is no such vote before the end of the DNC (currently scheduled to end Aug 22nd), this market resolves to "No vote happens".