In their joint television interview on Thursday night, Vice President Kamala Harris and Gov. Tim Walz of Minnesota were seated in a way that made him appear twice her height. But Mr. Walz understood his main assignment: Don’t overshadow your running mate.

Still, in his scarce speaking time — about 705 words in all — as he was pressed to answer for past misstatements and exaggerations, or to answer personal questions, he managed to deflect and then appeal to a broader point.

“I certainly own my mistakes when I make them,” Mr. Walz said, closing out a somewhat meandering answer to questions about inconsistencies in his past descriptions of his military service, a 1995 drunk-driving arrest and the fertility treatment that he and his wife used to conceive their children.

The CNN interview, of course, was mostly a test of Ms. Harris. Mr. Walz has made it abundantly clear, in the last three and a half weeks, that he does not need to be the center of attention — a defining feature of his candidacy is a lack of naked personal ambition, paired with effusive enthusiasm for his running mate.

He appears happy to be the guy sitting off to the side, just out of frame, perfectly content to be ignored — he did not speak for long stretches of the interview — but also happy to help.

Mr. Walz’s presence was somewhat unusual. It was Ms. Harris’s first television interview since President Biden dropped out of the race, and the fact that she brought Mr. Walz along with her, like a wingman, did not go unremarked by her opponent. On Thursday morning, former President Donald J. Trump criticized her for having Mr. Walz there.