John McCain's top foreign-policy adviser, Randy Scheunemann, is a leading expert on U.S.-allied Georgia -- and was a paid lobbyist for the former Soviet republic until March, in the run-up to what has become a major battle between Georgia and Russia.

Democratic rival Barack Obama's presidential campaign was quick to try to paint Mr. Scheunemann's dual roles as a conflict of interest after Sen. McCain swiftly took Georgia's side in the dispute, and cited it as evidence that Sen. McCain is "ensconced in a lobbyist culture,"...