The alleged harassment occurred after a luncheon at a private home before Baker Kline and other writers attended a fundraiser for the Barbara Bush Foundation.
"President Bush put his arm around me, low on my back…and squeezed my butt, hard, just as the photographer snapped the photo," Baker Kline wrote in an article for Slate Magazine. "Instinctively, I swiped his hand away.”
Bush spokesman Jim McGrath said earlier this week that the president was just trying to put people "at ease", responding to other allegations from women.
"At age 93, President Bush has been confined to a wheelchair for roughly five years, so his arm falls on the lower waist of people with whom he takes pictures...and on occasion, he has patted women's rears in what he intended to be a good-natured manner. Some have seen it as innocent; others clearly view it as inappropriate. To anyone he has offended, President Bush apologizes most sincerely,” McGrath said in a statement.
Earlier in the week, American actresses Jordana Grolnick and Heather Lind also claimed that Bush touched them from behind and made dirty jokes during photo-ops.
The accusations came under the trending #MeToo hashtag, which is being used by women on social media to share personal experiences of sexual harassment and assault.
It spread following sexual assault allegations that were leveled at Hollywood producer Harvey Weinstein by a number of women.
More about: #bush