In this photo taken June 1, 2012, then-Romney Campaign Senior Adviser Ed Gillespie poses for a photo at Romney campaign headquarters in Boston. (Josh Reynolds/AP)

Republican strategist Ed Gillespie’s plans to challenge Sen. Mark R. Warner (D-Va.) will likely transform what was widely expected to be a cakewalk for the incumbent into one of the most closely watched and interesting contests of the year.

Gillespie, the former lobbyist, Republican National Committee head and Bush White House aide, has told some Virginia Republicans that he will announce this month his plans to challenge Warner, a former governor who is seeking his second Senate term.

Gillespie’s announcement will instantly change the race into a matchup of two national figures with strong fundraising skills. In a bellwether state that both parties are eager to control, it will also give Virginia’s divided Republican Party a glimmer of hope after being swept in November’s races for governor, lieutenant governor and attorney general.

“Mark Warner’s not turned out to be the senator so many Virginians hoped he would be,” Gillespie said. “They hoped he’d be an independent voice, but he’s voted with President Obama 97 percent of the time since he got elected with him in 2008.”

Gillespie’s entrance into the race, however, doesn’t come close to propelling it to the top of the list of competitive midterm elections, according to analysts and polls. A September poll from Quinnipiac University put Warner’s job approval rating at 61 percent, well above any other Virginia officeholder.

U.S. Senator Mark Warner is seen Nov. 20, 2012. (Stelios Varias/Reuters)

Warner, 59, also begins 2014 with a campaign war chest of $7.1 million. With a net worth of at least $100 million, according to a Center for Responsive Politics tally, Warner is capable of outspending virtually any opponent.

“Even in a year where Republicans need to gain six seats to win the Senate, this race is probably not going to determine which party wins the majority,” Kyle Kondik, the managing editor of Sabato’s Crystal Ball at the University of Virginia, wrote Friday. “If Gillespie pulls the upset, he’ll probably be more like the 55th Republican Senate seat in the next Congress, not the 51st. . . . Gillespie needs a GOP wave or for Warner to make a very costly mistake or two.”

Gillespie, 52, is betting that the enduringly popular Warner will become less so once Republicans tie him to the federal health-care law and poke holes in his reputation as an independent-minded moderate.

Chris LaCivita, a longtime GOP consultant in Virginia, contends that Warner has “gotten a pass” for years and has never faced a genuinely tough opponent in a difficult environment.

“It’s important that you have a candidate who can articulate the differences, can articulate the issues and also has the ability to raise the funds to put together an effective operation,” LaCivita said. “Ed meets all those criteria.”

Republicans who have spoken to Gillespie say he is aware of the hurdles ahead. He may be a first-time candidate, but he is not new to politics.

“He’s not some neophyte that doesn’t understand how tough this race would be,” said another Republican consultant who knows Gillespie well.

Democrats are ready with a strategy to use against Gillespie. They plan to characterize him as more Washington than Virginia, a professional insider with questionable business ties and scant record of service.

That was how Gov. Terry McAuliffe’s opponents cast him in 2009, when he lost in the Democratic primary for Virginia governor, and again in 2013, when he won the commonwealth’s top job.

“Ed Gillespie is Terry McAuliffe four years ago, not Terry McAuliffe in 2013,” said Geoff Garin, the pollster for Warner and McAuliffe. “After [2009] he spent every day for four years getting to know Virginia and demonstrating his commitment to Virginia.”

Before he can face Warner, Gillespie must secure the Republican nomination at a June state party convention in Roanoke. So far, two other GOP candidates are running: former Pentagon official and lobbyist Howie Lind, and financial planner Shak Hill.

Unlike in a primary, the biggest and best-funded campaign won’t necessarily prevail at a convention typically stocked with a small crowd of conservative activists. But there is little sign so far that Lind or Hill will have the grass-roots support to beat Gillespie.

Gillespie has closer ties to in-state Republicans than McAuliffe did with Virginia Democrats in 2009, and he has helped funnel money to campaigns in the commonwealth via his post as chairman of the Republican State Leadership Committee.

Gillespie has a tight relationship with former governor Robert F. McDonnell (R) — he chaired McDonnell’s 2009 campaign — as well as with McDonnell’s top political aide, Phil Cox.

Cox and Leadership Committee President Chris Jankowski are likely to provide key informal advice to Gillespie’s campaign, and Gillespie is said to be eyeing some of the people who staffed state Sen. Mark D. Obenshain’s unsuccessful campaign for attorney general.

But for all his links to the party establishment, Gillespie never publicly took sides in the ideological battle that has flared within the Virginia GOP in recent years.

After allies of Ken Cuccinelli II maneuvered to change last year’s nomination method for governor from a primary to convention, Lt. Gov. Bill Bolling dropped out of the contest and spent the ensuing months accusing his party of moving too far to the right.

Some Republicans agree, thinking the attorney general lost because he was too conservative and that holding a convention — which resulted in controversial Chesapeake minister E.W. Jackson winning the lieutenant governor nomination — was a disaster. Conservatives have fired back that party leaders erred by giving up too soon on Cuccinelli, who lost on Election Day by less than three points.

Gillespie largely stayed out of that fight. He has close ties to antiabortion groups, gun rights advocates and other key players on the right. He also is connected to the more moderate Republican business community, and he was a co-founder of American Crossroads, a group that has battled tea party-favored candidates in some states.

At a town hall forum in Reston on Friday, Warner declined to talk about the prospect of a Gillespie challenge. But he did discuss the charge that he is vulnerable for his position on the Affordable Care Act.

Obama has been pummeled for promising that Americans would be allowed to keep their existing health plans — and Warner has been criticized for saying, on video, “Let me make clear, I’m not going to support a health-care reform plan that’s going to take away health care you’ve got right now or a health plan you like.”

Asked Friday whether he regretted his comment, Warner said he thought “the original grandfather clause” — about existing health plans — “could have been interpreted in a better way.”

Warner said he was working with a bipartisan group of senators on a package of “legislative fixes” to the law.

“I’ve invested in 50 businesses, at least,” he said. “Not a single business I invested in ever met their full original business plan. . . . This was a very imperfect piece of legislation, and it’s going to need fixes.”

Democrats will seek to muddy the waters on health care by pointing to Gillespie’s complicated past views on the issue. In 2007, Gillespie lobbied for a group called the Coalition to Advance Healthcare Reform which, among other things, called for ”universal coverage with individual responsibility.”

Garin said Democrats would also try to tarnish Gillespie’s record in the private sector — and dub him a “hired-gun lobbyist,” highlighting his work for Enron and other potentially controversial clients.

“There is a double burden on Ed Gillespie, or whoever the challenger will be, to make the case that Warner for some reason does not deserve to be reelected,” Garin said. “And even if they are successful in that case . . . they still have to make a case that they would be a better choice.”