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On the Ryan Campaign Plane-Joe Biden's stand in for Paul Ryan's debate prep will be Ted Olson, according to Ryan spokesperson Brendan Buck.

The Republican attorney famously argued in federal court for same sex marriage and against Proposition 8. Paul Ryan is against same sex marriage.

At a LGBT dinner in Washington D.C. in March, the renowned attorney called the battle against Proposition 8 "the highlight of my life" and "this is the most important thing we've done in our lives," according to the Washington Post.

The two have already squared off once this week, which is notable because it marks a difficult anniversary for the attorney: his wife was killed in the attacks of Sept. 11, 2001.

Ryan officially started debate prep last Sunday in Portland, Ore., but Olson was not on hand for that session.

Buck told ABC News that Olson and Ryan do not know each other well.

Olson served as Solicitor General in the George W. Bush administration, and as Assistant Attorney General for the Office of Legal Counsel in the Administration of Ronald Reagan.

He also served as private counsel to both Bush and Reagan. He helped to cement Bush's victory in the 2000 presidential election during the recount. He is now an attorney at the Gibson Dunn and Crutcher's law firm in Washington D.C.

Olson is close with former Vice President Dick Cheney, who is also a supporter of same sex marriage. His daughter Mary married her partner Heather Poe in June.

Ryan spokesperson Brendan Buck praised Olson as "just the kind of opponent needed to prepare the Congressman for Mr. Biden."

"Joe Biden has been in elected office for more than 40 years. There are few people in politics with more experience debating the issues than Joe Biden, so we are taking this process seriously. Mr. Olson is one of the most skilled, intelligent, and successful litigators in America - just the kind of opponent needed to prepare the Congressman for Mr. Biden," Buck said in a statement.

Biden has asked Democratic Rep. Chris Van Hollen of Maryland to play Ryan in his debate prep while Romney has tapped Ohio Sen. Rob Portman to play Obama for his debate preparations.

Ryan and Biden will face off at the vice presidential debate on Oct. 11 moderated by ABC News' Martha Raddatz.