Boyd Marcus grew up in a Leesburg home where politics wasn’t much discussed, but he asked his dad in 1960 which way he was voting: Nixon or Kennedy?

Nixon, his dad said, so 8-year-old Boyd concluded that his was a Republican household.

Only years later — after throwing himself into his college GOP club — did Marcus discover that his father didn’t consider himself a Republican at all, but a “Byrd Democrat,” an Old Dominion brand that liked Republicans for president but Democrats for everything else.

“I was startled to find out my father wasn’t as Republican as I thought,” Marcus said.

Now 61 and one of Virginia’s best-known GOP strategists, Marcus gave his own shock to political observers last month by endorsing and going to work for Terry McAuliffe, the former Democratic National Committee chairman running for governor.

In this Oct. 8, 2012, photo, former U.S. Sen. George Allen, left, looks around the debate stage with adviser Boyd Marcus in Richmond, Va. (Steve Helber/AP)

The defection of the veteran GOP strategist — adviser to former governors James S. Gilmore III and George Allen, among many others over the past 30 years — left Republicans stunned and, in some cases, enraged.

Democrats and even some Republicans see Marcus’s move as emblematic of a deep rift within the party: Marcus had been aligned with pragmatic establishment figures and repelled by the resolute tea party style embraced by Attorney General Ken Cuccinelli II, the Republican nominee.

“I’ve never known him to work for a Democrat, but it’s a different dynamic out there this year,” said state Sen. Emmett W. Hanger (R-Augusta), a social conservative and fiscal moderate who supports Cuccinelli but also pines for a more compromising GOP. “We’re in a different time for the Republican Party.”

Said Gilmore, who also backs Cuccinelli: “It’s clear to me that Boyd does not think that the direction of the party is what he would like to see it be.”

One of Marcus’s tasks for McAuliffe will be to encourage other Republicans to endorse him, the candidate said in an interview Friday. The Democrat has promised that more supporters like Marcus will emerge between now and Nov. 5. If Marcus helps deliver them, it could not only burnish his new political identity but punctuate for voters what some describe as Cuccinelli’s narrow ideological appeal.

“I’m not bringing a rigid ideological agenda,” McAuliffe said. “And I think for some Republicans, they’ve realized that there’s no room for them [in the GOP] anymore.”

GOP leaders and Cuccinelli’s campaign portray Marcus’s realignment quite differently: as a sellout.

More Post coverage of the race for Virginia governor.

Comparing Marcus to Benedict Arnold and Judas Iscariot, they said McAuliffe is trying to buy the image of bipartisan appeal. And there is an element of sour grapes, critics said, because Cuccinelli had outmaneuvered Marcus’s client, Lt. Gov. Bill Bolling (R), for the nomination. They said that Marcus, who hasn’t had a big win in a while, was simply hard up for work.

“Consultants aren’t immune to the economic downturns, and in the Obama economy people often have to take whatever jobs they can find,” said Pat Mullins, chairman of the Republican Party of Virginia.

In an interview shortly after his announcement, Marcus declined to discuss Cuccinelli but said McAuliffe has a more pragmatic approach that’s better suited to governing.

“You’ve got to have somebody as governor who can work with people and get the job done, and that’s the final bottom line,” Marcus said. “This is not sending somebody to the U.S. Senate to vote no.”

Although the figure will appear on disclosure statements, Marcus declined to say what McAuliffe is paying him.

Part of the shock over Marcus’s switch stems from his impeccably conservative credentials. He is no “Republican in name only,” or RINO, as the right calls moderate party members.

“He’s kind of like the uber-
Republican,” said Sen. Timothy M. Kaine (D-Va.), who was on the receiving end of Marcus’s strategies in his Senate race last year.

Marcus advised Allen’s winning bid for governor in 1993 and his failed one for Senate last year. In between, he helped a long-shot Republican primary challenger try to beat up Sen. John Warner for supporting gun control and opposing Supreme Court nominee Robert Bork. He also played hardball as Gilmore’s chief of staff and as consultant to countless state House and Senate races.

Warner dubbed him the “prince of darkness.” Even after jumping over to team McAuliffe, Marcus described himself this way: “I’m a conservative Republican.”

“Five or 10 years ago, I was very comfortable saying only a small group in the party was more conservative than I was,” Marcus said. But in the years since, Republican newcomers have lined up to his right.

Marcus has moved to the left in one area, gay rights, prompted by a longtime friend’s coming out.

“I was best man at a gay wedding last year, and 10 years ago I couldn’t have imagined that,” he said.

Aside from that, Marcus said he’s still the same low-tax, small-government, “pretty pro-life” prince that Democratic insiders loved to hate. Which has made his leap to the McAuliffe camp especially puzzling, even to Republican moderates who might seem to be easier pickings for McAuliffe.

“It’s shocking to me,” said C. Daniel Clemente, a Tysons Corner developer who has big differences with Cuccinelli — “I don’t support any of Cuccinelli’s social issues. None,” he said — but still prefers him to McAuliffe because of the attorney general’s government experience.

Marcus’s decision also was a stunner because of the professional consequences. The move forced him to sever ties with Republican clients and dissolve his 20-year partnership with consultant Ray Allen.

“A contributor can get away with it [switching parties] because everyone’s always happy to get their money,” said former lieutenant governor John Hager (R). “But anybody that’s involved with the party . . . has a hard time with somebody defecting and then just wanting to come back.”

But Hager said Marcus made the switch with his eyes open.

“He knows what the consequences are better than we do, but he made that decision,” Hager said. “Boyd’s a smart man. I’m sure he weighed the downside and made his own decision.”