WASHINGTON -- A conservative columnist who welcomed Sarah Palin's entry in national politics says she's proven to be a dud and should step aside as John McCain's running mate.

Kathleen Parker,writing in the National Review Online, says her "cringe reflex is exhausted" after watching the Alaska governor stumble through TV interviews and it's become clear to her that Palin is out of her league.

No one hates saying that more than I do," Parker writes. "Like so many women, I've been pulling for Palin, wishing her the best, hoping she will  perform brilliantly. I've also noticed that I watch her interviews with the held breath of an anxious parent, my finger poised over the mute button in case it gets too painful. Unfortunately, it often does.""

"Palin, new to national politics, boosted Republican presidential nominee John McCain in polls and excited the party's core conservatives when he chose the first-term governor for his ticket. Some of that shine has since worn off in polls.

Parker said she thought Palin was a "refreshing feminist of a different order" when she joined the ticket, but it's become clear she doesn't know enough about economics or foreign policy to be president should that become necessary in a McCain administration.