beat a dead horse

Idioms  

1. Also, flog a dead horse. Try to revive interest in a hopeless issue. For example, Politicians who favor the old single-tax idea are beating a dead horse. From the 1600s on the term dead horse was used figuratively to mean “something of no current value,” specifically an advance in pay or other debt that had to be worked (“flogged”) off. [Second half of 1800s]

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Example Sentences

“I don’t want to beat a dead horse, but we tried like heck to acquire Khalil Mack,” Lynch said in an interview with 95.7 The Game last month.

From Los Angeles Times • Dec. 17, 2018

Aronofsky’s point was made about an hour into the film, but he proceeded to beat a dead horse for the remaining hour.

From New York Times • Sep. 20, 2017

Not to beat a dead horse, but — hand me that two-by-four — the Nats had used 11 men in their bullpen this season before seeking desperate reinforcements.

From Washington Post • Aug. 6, 2017

I don’t want to beat a dead horse, but I really want her to get this and pay attention to my needs.

From Slate • Feb. 27, 2017

Only if you’re Roger Federer. beat a dead horse.

From "Woe Is I" by Patricia T. O'Conner