In a move that wasn't entirely unexpected, presumptive GOP presidential nominee Sen. John McCain endorsed Thursday the controversial California Marriage Protection Act initiative expected to go before the state's voters this November.

In an e-mail received by the ProtectMarriage.com campaign McCain issued the following statement:

"I support the efforts of the people of California to recognize marriage as a unique institution between a man and a woman, just as we did in my home state of Arizona," McCain said in a message widely distributed via PRNewswire. "I do not believe judges should be making these decisions."

Commenting on the endorsement, ProtectMarriage.com Chairman Ron Prentice said:

"Sen. McCain's position will be an important factor to millions of Californians. (He) has articulated a key feature of the initiative campaign, which is that voters and not judges should be determining this issue."

McCain's endorsement comes on the heels of the California Supreme Court's May 15 ruling legalizing same-sex marriage in the state.

The measure, which would amend the state's constitution if passed, is expected to be one of the most-watched initiatives on the state's November ballot.