Virginia Republicans seemed to be heading into 2012 as the epitome of unity.

The party took control of both the General Assembly and the executive mansion for only the second time since the Civil War. The state’s popular governor, Robert F. McDonnell, is frequently mentioned as a possible vice presidential nominee. Bill Bolling, the insurance executive turned lieutenant governor, was part of a succession deal.

Enter Republican Attorney General Ken Cuccinelli II.

The outspoken Cuccinelli upended the governor’s race with a surprise challenge to Bolling in next year’s gubernatorial contest.

Since Cuccinelli’s announcement, Bolling has refocused a network of volunteers and embarked on a fundraising tour, while Cuccinelli has hired campaign consultants and pursued support from powerful business leaders.

Cuccinelli has uncharacteristically declined to comment on the race. But Bolling has lashed out, expressing his disappointment with his rival’s decision to get in the race and deriding him for putting his “personal ambition” ahead of the state.

Now, many Virginia Republicans are bracing for a bitter and expensive primary fight that threatens to divide the party — much like the presidential race has done for the GOP nationally — and change the trajectory of a state they control.

“It’s been some of the same angst, same split in the party as when I ran,’’ said former lieutenant governor John Hager, who ran for governor in 2001 but lost in a convention to a candidate who was perceived as more conservative. “The Republican Party is too easy to split. . . . But the splits change over time.”

At the heart of the dispute is a struggle that torments many Republicans both in Virginia and the rest of the country: whether to vote for a candidate who energizes them by pursuing conservative causes or one who appeals to more moderate voters by focusing on the economy.

Several rank-and-file activists have lined up behind Bolling or Cuccinelli, though McDonnell has urged a measured approach this early in the process. Party leaders say they are largely neutral in hopes that Republicans will quickly unify behind a nominee to defeat a Democrat looking to take back the governor’s mansion.

“The Republican Party in Virginia is diverse,’’ said former governor James S. Gilmore III, who nearly lost the party nomination for U.S. Senate against a more conservative candidate in 2008. “Democrats have an advantage in that they are unified in what they are trying to accomplish.’’

Stylistic differences

Bolling and Cuccinelli are cut from the same conservative cloth — both winning elections to the state Senate, where they served four years together.

Bolling, chairman of the Hanover County Board of Supervisors, knocked off a longtime Democratic incumbent in 1995 in what was becoming an increasingly suburban and Republican district outside Richmond.

Cuccinelli, a lawyer from Centreville, defeated a Democrat for an open seat in 2002, in part by campaigning against a sales-tax increase to pay for roads. He became the only Republican senator in increasingly Democratic Fairfax County.

Both support expanding gun rights and curbing illegal immigration, and oppose abortion and tax increases. Even supporters are hard-pressed to find policy differences between them.

Often, though, their differences come down to style.

Cuccinelli has mainly overshadowed Bolling — and even McDonnell, at times — with persistent lawsuits against the federal government, challenges to scientists on climate warming and advice to colleges against nondiscrimination policies for homosexuals. His tendency to speak his mind has helped him garner enthusiastic tea party support. On Thursday, he received the “Defender of the Constitution Award” at the Conservative Political Action Conference, billed as the largest gathering of conservative leaders and activists nationwide.

“Ken has built up a lot of street cred with the tea party. He’s been here,’’ said Mark Kevin Lloyd, chairman of the Virginia Federation of Tea Party Patriots, a statewide umbrella group. “Bill Bolling has kept his distance. He wants consensus — consensus more than principles. We can’t sing ‘Kumbaya’ all the time.’’

Bolling, 54, has been an understated key adviser to McDonnell, serving as the state’s chief jobs- creation officer and stressing kitchen-table issues, such as the economy, transportation and higher education. He has led in the hue of McDonnell, who has governed like a moderate, managing to mainly retain Republican support while attracting independents, even some Democrats.

Until this year. Bolling now presides over an equally divided Senate and has cast seven crucial tie-breaking votes.

“He’s talking about issues that matter to average citizens,’’ said supporter James Rich, a longtime Republican activist in Fauquier County.

Political observers say Cuccinelli has tapped into the anger and resentment many Republicans feel toward big-government, gridlocked Washington — much like presidential hopeful Newt Gingrich has done. Former Massachusetts governor Mitt Romney, backed by Bolling and McDonnell, has been considered the front-runner for months. But Republican voters appear to continue to search for the anti-Romney alternative — mostly recently former House speaker Gingrich and former senator Rick Santorum (Pa.).

Cuccinelli is “the heart and soul of the party,’’ said former congressman Tom Davis, a moderate Republican from Virginia who has advised both Bolling and Cuccinelli but has publicly stayed out of the race.

Cuccinelli declined to comment on the governor’s race, saying he is focused on the 2012 contests, although he has not endorsed candidates. Bolling said in an interview that he has strong backing from those who support “results-orientated conservatism.”

“I am a principled conservative, but I’m not a rigid ideologue,’’ he said in a thinly veiled jab at Cuccinelli. “I focus on working with people to get things done, not on confrontational politics. If you want a guy that’s going to break the dishes, that’s not me. If you want a guy that’s going to get things done and build a better Virginia, that is me.’’

Bolling said he has ratcheted up his attempts to raise funds and organize volunteers and supporters across the state. “It makes us do stuff more quickly than we had anticipated,’’ he said.

Sparse words exchanged

Bolling and McDonnell struck a deal three years ago: McDonnell, then attorney general, would run unopposed for the GOP nomination for governor if, four years later, McDonnell would back Bolling for the job.

Some Bolling supporters say his selfless act brought the party together and helped McDonnell to defeat his Democratic challenger in 2009.

“He doesn’t always do things that put him in the headlines,’’ said Michael Ginsberg, who leads a group of Republicans in the 8th Congressional District in Northern Virginia. “It was a unifying thing for the party.”

But Cuccinelli was not part of the deal.

Cuccinelli, 43, had said he would run for reelection and flirted with taking on U.S. Sen. Mark R. Warner (D) in 2014 but ultimately decided to run for governor despite some Republicans saying he should run later.

“I think there is a sense in the party that these offices are not inherited,’’ said Michael Giere, a Republican activist from Falls Church who supports Cuccinelli. “What you’re seeing is a new, bolder conservative politics.’’

Cuccinelli called Bolling in December just hours after telling his staff that he would run for the top job. Bolling did not return the call.

After Cuccinelli’s announcement, the two did not speak for a month. They crossed paths during the first week of the legislative session this year, but Bolling said they just made small talk. Two weeks ago, they appeared at a business breakfast in Richmond. They acknowledged each other, and Bolling garnered some laughs when he joked that the two were in competition — on who could give the shortest speech.

McDonnell, who meets with Bolling and Cuccinelli frequently, said that he has told both men they should move past their political aspirations and work together to complete a successful legislative session and help elect a Republican president and U.S. senator in November.

“I have said it publicly and privately. I don’t want anything to get in the way of having a successful session where we have got only the second chance in history of having a Republican administration and a Republican legislature work together,” McDonnell said.

Instead, Bolling issued two scathing statements about Cuccinelli — one responding to his decision to run for governor and another on the attorney general’s change of heart about getting more presidential candidates on the state’s GOP primary ballot.

“Unfortunately, he has now decided to put his own personal ambition ahead of the best interests of the commonwealth and the Republican Party,” Bolling said.

Primary vs. convention

Political observers say Cuccinelli has the edge in the primary election but could have a difficult time in a general election, when successful Republican candidates often play down their conservative credentials.

Some Cuccinelli supporters have said they are interested in reversing the party’s decision to hold a primary rather than a convention to select the gubernatorial nominee.

Cuccinelli backed a convention, where he would have an advantage because the nominee would be chosen by party insiders. Bolling supported a primary, which could favor him because it would be open to all Republican voters.

But Cuccinelli had said he is not interested in revisiting that decision, although that doesn’t preclude the GOP’s governing board from doing so.

Meanwhile, several Democrats have expressed an interest in statewide office, but only former Democratic National Committee chairman and businessman Terry McAuliffe has told supporters he will likely run for governor for a second time.

“I’m not into this — and never have been — that idea that someone deserves this or that,’’ McAuliffe said in an interview. “It will be a healthy debate. . . . It will be good for the commonwealth, good for the party, good for everybody.”

Hager wouldn’t disagree, but he said he knows what Republicans need to do to win.

“We need to be unified by the time we have a nominee,” said Hager, who has not endorsed a candidate. “We will have been successful if we unify.”

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