Under Trump, could a legal action for Writ of Mandamus be used

[no_hypocrisy]

to force an agency to do its job?

Example: the Office overseeing Medicare cuts benefits by 50% despite funding being available.

Could a Medicare beneficiary/group of beneficiaries/organization (e.g., AARP) sue that office to compel it to do its statutory duties?

Writ of Mandamus was the device used in Marbury v. Madison, when Jefferson refused to seat an individual to his office, appointed by outgoing President John Adams. SCOTUS made Jefferson seat him.

A (writ of) mandamus is an order from a court to an inferior government official ordering the government official to properly fulfill their official duties or correct an abuse of discretion. See e.g. Cheney v. United States Dist. Court For D.C. (2004). According to the U.S. Department of Justice, "Mandamus is an extraordinary remedy, which should only be used in exceptional circumstances of peculiar emergency or public importance."
https://www.law.cornell.edu/wex/mandamus#:~:text=A%20(writ%20of)%20mandamus%20is,United%20States%20Dist.

[FBaggins]

1. There will be lots of those attempted

Just remember that those have to go through the federal court system and they control the top of that pyramid

[no_hypocrisy]

2. Perhaps with the benefit of "stays" to freeze the deleterious actions.

And we all know how slow the pace of the judiciary is.

Unless SCOTUS can find an "exception" not to apply WOM, it will essentially overrule the bedrock of the American Judiciary, Marbury v. Madison, perhaps imperiling simultaneously the principle that only the U.S. Supreme Court and lower courts can interpret The Constitution.

[NJCher]

4. Thanks, Captain Obvious

[sop]

3. If Trump tries to cut Medicare benefits in half he'll have a lot more to worry about than a Writ of Mandamus.

Lobbyists for the entire Medical Industrial Complex in this country would put tremendous pressure on Congress to stop it.