S. 1516 — Cahokia Mounds Mississippian Culture Study Act

2%becomes law moderate confidencepending: Senate reported

Cahokia Mounds Mississippian Culture Study Act — reported and queued, quiet for 122 days; 7% to reach the floor, 2% to become law.

reaches a floor vote

99%

passes if voted (stage model)

26%

survives downstream

becomes law

The gap: on the floor this would pass — 47% by the member-vote simulation — but the floor is the hard part: 7% to ever get the vote. That gap, not the whip count, is the story.

If it reaches the floor

majority

60 (cloture)

Projected 63 yea of 100 voting; 90% interval 31–95 (quartiles 51–78). Intervals are backtest-verified to cover ~90%.

Filibusterable: the realistic Senate line is 60 votes — P(≥60) = 47% (simple-majority P = 82%).

By floor procedure

No vote is scheduled, so the headline marginalizes over how the Senate would take it up; the branches:

Procedure	Likelihood	Projected yea	Passes
conference	5%	67 [37–97]	86%
passage	95%	62 [31–95]	81%

Receipts

Sponsor: Richard J. Durbin (D). Latest action (2026-02-04): Committee on Energy and Natural Resources. Ordered to be reported with an amendment in the nature of a substitute favorably.
Full record: Congress.gov.

Forecast run predict-20260606T193507Z · models member-vote-1.0.0-t117d118-20260606 + passage-1.0.0-t117d118-20260606 · conditional whip forecasts for the Senate run at moderate confidence (why).