J.D. Vance has told some whoppers — so does it stick when he calls someone else a liar?

Since Vice President Kamala Harris on Aug. 6 tapped Minnesota Gov. Tim Walz to be her running mate, Ohio Sen. J.D. Vance has been attacking Walz’s credibility.

Vance has questioned Walz’s honesty about his military service, and the artificial insemination method Walz and his wife used.

“Why lie about it?” Vance said to reporters last week when asked about Walz’s statements conflating in-vitro fertilization with intrauterine insemination.

The former method was not the one used by Walz and his wife...