stubborn as a mule

Related to stubborn as a mule: same old same old, To Say the Least, worse for wear

(as) stubborn as a mule

Extremely reluctant or unwilling to change a particular opinion, behavior, or course of action, especially when faced with opposition. My toddler is as stubborn as a mule, and he'll throw a tantrum any time he doesn't get what he wants. You'll never get Rich to change his opinion—he's stubborn as a mule.
See also: mule, stubborn
Farlex Dictionary of Idioms.

*stubborn as a mule

 and *obstinate as a mule
Cliché very stubborn. (*Also: as ~.) I tried to convince Jake to go to the doctor, but he's as stubborn as a mule. For four years, Henry pestered his parents to let him learn the trumpet. They tried to talk him into some other, quieter instrument, but he was stubborn as a mule, and now he has a trumpet.
See also: mule, stubborn
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

stubborn as a mule

Extremely obstinate, as in He's stubborn as a mule about wearing a suit and tie. This simile evokes the proverbial stubbornness of mules, whose use as draft animals was once so common that the reputation for obstinacy can hardly be as warranted as the term indicates. [Early 1800s]
See also: mule, stubborn
The American Heritage® Dictionary of Idioms by Christine Ammer.

stubborn as a mule

If someone is as stubborn as a mule, they are determined to do what they want and very unwilling to change their mind. For all his pleasant manner, the Texan was stubborn as a mule, and he didn't like being pushed. Old Greg is also stubborn as a mule. He won't say anything — he'll just carry on doing what he planned. Note: This expression is usually used to show disapproval.
See also: mule, stubborn
Collins COBUILD Idioms Dictionary, 3rd ed.

stubborn as a mule

extremely stubborn. informal
See also: mule, stubborn
Farlex Partner Idioms Dictionary

(as) ˌstubborn as a ˈmule

(often disapproving) very determined not to change your opinion or attitude; obstinate: If you tell her what to do, she won’t do it because she’s as stubborn as a mule. Why not just suggest it to her?
See also: mule, stubborn
Farlex Partner Idioms Dictionary

stubborn as a mule

Singularly obstinate. No one knows why mules in particular have been singled out for this quality, but they have, for centuries. “Contrary” and “obstinate” are other adjectives used in the simile, which became current in the early 1800s and remains so. The same is meant by the adjective mulish.
See also: mule, stubborn
The Dictionary of Clichés by Christine Ammer
See also:
  • (as) obstinate as a mule
  • (as) stubborn as a mule
  • mule
  • obstinate
  • stubborn
  • be (as) stubborn as a mule
  • cooperate on (something) with (someone or something)
  • cooperate with (someone or something) on (something)
  • cooperate with
  • cooperate with (someone or something)