(The Hill) — Don Lemon says he regrets the way he talked about “women in their prime” during a segment on CNN’s morning show on Thursday.

“The reference I made to a woman’s ‘prime’ this morning was inartful and irrelevant, as colleagues and loved ones have pointed out, and I regret it,” Lemon wrote in a tweet on Thursday afternoon, following his remarks on “CNN This Morning.”

“A woman’s age doesn’t define her either personally or professionally. I have countless women in my life who prove that every day,” he continued.

Lemon was widely panned for comments made hours earlier about Republican presidential candidate Nikki Haley, who called for competency tests for politicians over 75 years old as part of her campaign launch earlier this week.

“This whole talk about age makes me uncomfortable. I think it’s the wrong road to go down. She says people, you know, politicians or something are not in their prime,” Lemon said on the air. “Nikki Haley isn’t in her prime, sorry.”

“A woman is considered to be in their prime in 20s and 30s and maybe 40s,” he added.

The host’s comments were met with immediate pushback from his female co-hosts and resounding scorn from critics, many on the political right, including Haley herself.

“Liberals can’t stand the idea of having competency tests for older politicians to make sure they can do the job,” said Haley, who also sent a fundraising e-mail about the CNN anchor’s comments. “[By the way], it’s always the liberals who are the most sexist.”

Lemon — who for years hosted a show in prime time at CNN — was tapped last fall by network leadership to host its revamped morning program. At the time, Lemon insisted he “was not demoted” and said he was looking forward to the new challenge.