"They":

• High-ranking Republicans with plausible knowledge by the candidate

• Militias like the Proud Boys count

• MAGA-aligned independent would count

"Attempt":

• Needs to have had a significant (>=10%) chance of success, according to traders' opinions

• Aborted plan or random document doesn't count

• Plan needs to be executed, or disrupted by law enforcement

"Coup" includes:

• Anything that makes the person they try to put in power illegitimate in my judgment, e.g. significant ballot-stuffing, significant amount of false electors

• Bush v. Gore would resolve YES

• Trump 2020 would resolve YES

• Effective control over the US, e.g. via AGI/superintelligence. For example, Trump family controlling AGI that has the US military beat, or otherwise de facto controls the country.

• Controversial & decisive judgment by the Supreme Court in favor of a Republican. (This one only counts if it succeeds with a Republican majority of Justices)

• Doesn't have to be violent or involve the military

Closes when it resolves yes or until a peaceful and successful transfer of power has occurred.

Edge case examples:

Edge Case 1:

Following the Republican loss, a state's Republican Secretary of State and some county officials begin "finding" large numbers of previously uncounted ballots in heavily Republican areas. The number would be enough to flip their swing state. When challenged, they insist these are legitimate ballots that were misplaced. Investigation shows signs of forgery but isn't conclusive. A group of MAGA-aligned election officials had been meeting privately in the months before, discussing "election integrity contingencies."

Because it would flip the state AND is a swing state, it would resolve YES IFF the evidence strongly supports forgery/foul play, such that a prediction market would be >90% (if the investigation is expect to conclude soon, I would wait for that). If it's a red state, it wouldn't resolve YES.

If this sub question resolves "YES, in favor of Republicans", this main question also resolves YES:

See ~50 related questions here:

https://manifold.markets/news/us-democracy

I don't bet on my questions with subjective criteria.