Cindy McCain's half sister is planning on voting for Barack Obama, she tells Usmagazine.com.

"I'm not voting for McCain," Kathleen Hensley Portalski tells Us. "I have a different political standpoint.

"I'm voting for Obama," the Phoenix resident says. "I think his proposals to improve the country are more positive and I'm not a big war believer."

Portalski, 65, and the potential first lady, 54, have the same father: Jim Hensley, the founder of the beer distributor Hensley and Co. that Cindy McCain now chairs.

In an interview with NPR News' All Things Considered last week, Portalski said she felt "like a non-person" after Cindy McCain described herself as an "only child."

Portalski's mother is Hensley's first wife; Cindy McCain's mother, Marguerite Hensley, also had another daughter from her first marriage.

"She's kinda cool, standoffish," Portalski tells Us of her half sister.

Portalski also doesn't expect Cindy McCain to make an effort to reconcile their relationship.

"She never has, and I doubt that she ever will," she tells Us.

Portalski's son Nathan, a 45-year-old aerospace machinist, is also backing Obama.

"I wouldn't vote for John McCain if he was a Democrat," he tells Us. "I would not vote at all before I'd vote for him.

"I question whether Cindy is someone I'd want to see in the White House as first lady," he adds.