Over the past year, dozens of celebrities from Kristin Cavallari to Steve-O to Kim Zolciak have posed for the "NOH8" photo campaign in an effort to overturn Proposition 8 and legalize same sex marriage in California.

The latest high-profile figure to take part in the initiative is a little more surprising: Sen. John McCain's wife, Cindy.

"I couldn't be more proud of my mother for posing for the NOH8 campaign," daughter Meghan McCain tweeted on Wednesday morning. "I think more Republicans need to start taking a stand for and civil rights in this country and set the example that this is not a partisan issue."

SLIDESHOW: The McCain Women and More Celebs in the NOH8 Campaign.

Cindy McCain's position stands in contrast to her husband's, the former GOP presidential nominee, who opposes gay marriage.

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Sen. McCain's office issued a statement Wednesday evening affirming his own stance on gay marriage without addressing the ad campaign directly.

“Senator McCain respects the views of members of his family. The Senator strongly supported the effort to successfully pass Arizona Proposition 102, the Marriage Protection Amendment, and his opposition to gay marriage remains the same. Senator McCain believes the sanctity of marriage is only defined as between one man and one woman.”

The photo shoot took place in the desert outside of Los Angeles last week, Pop Tarts has learned. Cindy McCain's desire to participate took photographer Adam Bouska by surprise.

"I was shooting the cover for Meghan's tell-all political book that she's writing, and her mother just came along for support, and suddenly asked if it was okay if she lent her face for the cause," Bouska told Pop Tarts. "We were definitely surprised. We always knew where Meghan stood on the issue (she was one of the first to pose and show her support in June last year), but we weren't sure about Cindy. She said it shouldn't matter what political party you are part of, that shouldn't be the issue that divides you."

Bouska also said the response he has received since releasing Cindy's photo has been overwhelming.

"Many people feel that she is taking a more progressive stance on gay marriage than Obama," he added. "I hope this will help people see that it is okay to be gay and a Republican. There are so many bigger issues like war and health care we have to worry about; we shouldn't have to be wasting time on this. It is basic human rights."

Meanwhile Meghan McCain is slated to be the keynote speaker during February's National Equality Week at George Washington University; although there was a misunderstanding as to whether or not she was still invited to attend given her opinion on the issue of gay marriage.

The GW College Republicans withdrew their co-sponsorship of the event after learning that she would be talking about Marriage Equality Week, not "what it means to be a Republican," as they originally were told.

McCain thought this meant her speaking engagement had been canceled, but later tweeted that "until further notice" she was still scheduled to speak at the university.

"The event is still occurring,"  Rob Noel, Communications Director at GW Republicans, told Pop Tarts. "[But] the GW College Republicans will not be co-sponsoring Meghan McCain's visit to GW to deliver the keynote address during Marriage Equality Week. Ms. McCain's views on marriage equality align with neither the Republican Party nor her father's personal stance. Though we fully supported John McCain's candidacy for President, we feel that Meghan McCain's last name is not near as important as the message she advocates."