Correction: An earlier version of this article mistakenly said Terry McAuliffe headed the Democratic National Committee during the 1990s. McAuliffe headed the DNC from 2001 to 2005, and was co-chairman of President Bill Clinton’s 1996 re-election campaign. This version has been updated.

Virginia’s gubernatorial races traditionally have been genteel affairs, featuring polite candidates extolling centrist views. But Lt. Gov. Bill Bolling’s decision Wednesday not to seek the Republican nomination for governor sets up an uncharacteristically partisan contest in an increasingly independent state.

Barring unforeseen opposition, Virginians will probably be left to decide next year between two outspoken candidates with national profiles: state Attorney General Ken Cuccinelli II (R), a conservative firebrand, and businessman Terry McAuliffe, who headed the national Democratic Party from 2001 until 2005.

Neither is the kind of candidate Virginians have tended to support in the commonwealth’s off-year elections for governor.

In fact, Bolling said Wednesday that he would not back Cuccinelli and did not dismiss a possible independent run.

“I have serious reservations about his ability to effectively and responsibly lead our state,” Bolling said of Cuccinelli. “Given those reservations, I could not in good conscience endorse his candidacy for governor.”

Former Democratic National Committee Chairman Terry McAuliffe, left, and GOP Attorney General Kenneth T. Cuccinelli II are, so far, the remaining contenders for their respective party nominations in Virginia’s gubernatorial contest. (Bob Brown, Steve Helber)

Bolling’s decision to drop out and U.S. Sen. Mark R. Warner’s announcement that he will not seek another term as governor have left the state’s electorate with a stark choice.

“Virginia’s very much a purple state,” said Jessica Taylor, a senior analyst with the Rothenberg Political Report. “Assuming Terry McAuliffe is the nominee, you have two people that aren’t really toward the center of the party. You have this growing independent base in Virginia, that’s really where the race could be won, and we haven’t really seen either one try to talk to that yet.”

Both candidates evoke strong partisan passions. As attorney general, Cuccinelli has gained national attention by challenging climate change research, going after the federal health-care overhaul in the courts and supporting stricter rules for the state’s abortion clinics. McAuliffe, a longtime McLean resident, has been viewed as a Virginia outsider and a Washington insider. During Bill Clinton’s presidency, he often appeared on TV talk shows to advocate the party line.

Cuccinelli gained a clear advantage over Bolling in June, when Cuccinelli’s supporters took control of the State Central Committee and changed the nomination method from a statewide primary to a party convention. Conventions, which are attended by party regulars, tend to favor conservatives.

Although the field is narrowing, with nearly a year to go until the next governor is chosen, it is not necessarily set.

Tareq Salahi, the vintner who was accused of crashing a state dinner at the White House, has said he plans to seek the GOP nomination, though he is not seen as a threat to Cuccinelli. And Democratic former congressman Tom Perriello has quietly approached prominent members of his party in recent weeks to let them know that he is at least considering the idea, according to people familiar with the talks.

Bolling said his party’s about-face on the nominating process “created too many obstacles for us to overcome.” He also said a divisive convention battle could do long-term harm to the state party, which was unsuccessful in the presidential and U.S. Senate contests this year.

Bolling pledged in his announcement to remain involved as “a more independent voice” in the campaign. The wording led some political observers to speculate that Bolling plans to make a bid as an independent.

In a brief interview Wednesday, Bolling said he had “no current intention to embark on an independent campaign for governor.” But he left open the possibility that he would do so as the race unfolds.

“This is a very unpredictable campaign, and I will be watching closely how it evolves,” he said.

The dynamic created by the lieutenant governor’s exit could lead to a brutally negative race aimed at turning out the base of each party.

Mo Elleithee, a national Democratic consultant, said Bolling’s decision to bow out “speaks volumes about the state of the Virginia Republican Party.”

“It seems to be the wrong lesson learned from 2012,” said Elleithee, who worked on McAuliffe’s 2009 campaign for the Democratic gubernatorial nomination and former governor Timothy M. Kaine’s successful U.S. Senate race this year. “Bill Bolling felt like he had absolutely no path and that the ideologues sort of had it locked up for Cuccinelli. In 2012, Virginians sent a pretty strong message that they didn’t want hyperpartisanship.”

McAuliffe is known as “a dealmaker,” said Jennifer Duffy, who analyzes gubernatorial races for the nonpartisan Cook Political Report, and Cuccinelli “is far more ideological in a lot of ways.”

“I think [Cuccinelli] walks around with a copy of the Constitution, and McAuliffe doesn’t,” she said.

Running in 2009 on the slogan “Bob’s for Jobs!,” Robert F. McDonnell rebranded himself as someone primarily focused on economic development. He managed to do that despite the unearthing of a master’s thesis in which he was critical of working women, gays and a Supreme Court decision legalizing the use of contraceptives by unmarried couples. McDonnell said during the campaign that his views had changed since he wrote the paper as an evangelical student in his 30s.

Some observers said McAuliffe might be able to recast himself as a pro-business moderate — “Mark Warner lite,” as one conservative put it — especially given the relatively centrist positions his friend Bill Clinton took as president. Taylor said that might work, even though as DNC chairman and as a candidate for governor in 2009, McAuliffe was no middle-of-the-road Democrat, she said.

“If he tries to talk about the Clinton years, that could have more of an appeal to centrists,” Taylor said.

McAuliffe may still have some work to do convincing Virginia Democrats that he is one of them — which he was not able to do four years ago when he sought the Democratic nomination. Notably, when Warner announced his decision to stay in the Senate, he did not endorse McAuliffe.

Republicans have signaled that they plan to recast McAuliffe as a carpetbagger, though he has worked to shore up grass-roots support in the state since 2009.

But no one imagines that Cuccinelli will try to play down his strong conservative stances against abortion, gay rights, “Obamacare” and climate change.

“Romneyesque hedging,” as one supporter put it, would ruin the Cuccinelli brand.

Still, Cuccinelli could make himself more appealing to swing voters by taking up new causes with the same zeal that helped him win tea party hearts, said Pete Snyder, a technology entrepreneur and Republican lieutenant governor candidate who oversaw the GOP’s 2012 campaign in Virginia.

“You won’t find Ken Cuccinelli going back on his principles,” Snyder said. “But I anticipate he’ll take that same warrior mentality to focus on reform issues — how the middle class has been getting ripped off — and he’ll defy expectations.”

Ben Pershing contributed to this report.