When tea party activist Jim Cohen heard that a former lobbyist and longtime Republican political strategist was seeking the party’s nomination for Senate, he immediately started doing opposition research.

“I was prepared to tea-party this guy,” Cohen said. “We were going to take him out.”

But Ed Gillespie reached out to Cohen, talked to him frequently and even stayed at his Virginia Beach home.

The approach is one reason Gillespie is by many accounts the front-runner to win the GOP nomination at the state party’s convention in Roanoke this weekend. Gillespie’s political savvy, experience and fundraising muscle make him a serious foe for Sen. Mark R. Warner (D-Va.), Republicans say.

That may be especially true in a year when Republicans hope to pick up seats in the Senate and attract voters eager to punish Democrats for President Obama’s perceived sins, from the Affordable Care Act to secret waiting lists at Veterans Affairs.

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Republicans say Obama’s weak points make Warner more vulnerable than in past years and a prime target for Gillespie’s network of national money men. Some Democrats also concede privately that Warner isn’t the unstoppable force he was as the state’s chief executive.

Officially, Democrats insist that Warner’s historic statewide popularity and ability to position himself as a business-minded “radical centrist” with bipartisan bona fides continue to serve him well in a state where his approval ratings as governor topped 70 percent. And they have one remarkable data point: With $9.4 million in his campaign war chest, Warner has a nearly 4-to-1 financial advantage over Gillespie, according to both candidates’ most recent filings.

“[Gillespie] picked the wrong guy to go up against. He’s in the ring with the 800-pound gorilla,” said state Senate Majority Leader Richard L. Saslaw (D-Fairfax). He predicted that Warner would take the race by eight points come November.

“First of all, Warner is really popular,” he said. “I mean, everybody likes him. Republicans like him, the Democrats, the independents — he’s just immensely popular. You’ve got to remember he’ll outraise and outspend Gillespie two to one, three to one. And let’s face it — Mark can write a big check if he needs to. It’s just not gonna happen.”

Gillespie will remind voters that Warner backed the federal health-care law, sides with the president most of the time and tries to have it both ways on emission standards released this week by the administration.

While Republicans mine Warner’s voting record, Democrats are combing through Gillespie’s background for evidence that he has supported the individual health-care mandate and did Enron’s dirty work before the company imploded (a reference to his past work lobbying for the failed energy giant). The Democratic Party of Virginia has already claimed gillespiecare.com and enroned.com on the Web.

Gillespie, who is the candidate and not the strategist for the first time in his career, admitted that he has had to develop a thicker skin — barbs sting more when it’s his name on the campaign signs.

But the veteran strategist, counselor to President George W. Bush and chairman of the Republican National Committee is as on-message as ever.

“I’m worried about the direction the country’s headed,” he said. “If we’re able to get control of the U.S. Senate in [Obama’s] last two years in office, that would have a very positive effect on the country. . . . Winning in Virginia would all but guarantee a majority in the Senate.”

As to the tea party, Gillespie said conservatives of all stripes share core principles.

“The more people are involved in the political process because they’re worried about too much government intrusion in our lives, too much debt, our taxes being too high, our constitutional principles, I think that’s a good thing for us,” he said.

The New Jersey-born son of grocery store owners, Gillespie started his political career on the lowest rung, parking cars in a Senate lot while attending Catholic University. In 1985, he was hired as press secretary to former Texas congressman Dick Armey, who — Gillespie notes in his book — played a key role in defeating then-first lady Hillary Rodham Clinton’s health-care proposal.

Gillespie later formed a lobbying firm with Jack Quinn, President Bill Clinton’s former White House counsel, a job he left eight years ago, sticking to strategic communications. Along the way, Karl Rove asked him to join the “Gang of Six,” advising Bush, which Gillespie calls a group of “party insiders” in his book. He helped write former House speaker Newt Gingrich’s Contract With America, ran the RNC and was a senior adviser to Mitt Romney’s 2012 presidential bid.

“Twenty-plus years as a Washington insider who trades money for influence makes you an excellent lobbyist, but a fatally flawed United States Senate candidate. The D.C. machine loses its effectiveness in a convention setting and the people gain the effectiveness,” said retired Air Force pilot Shak Hill, one of three Republicans trying to keep Gillespie from the nomination. Also in the running are businessman Chuck Moss; and Tony DeTora, a policy adviser to Rep. Dana Rohrabacher (R-Calif.).

On Saturday, several thousand party faithful will gather to choose a nominee. Last year, the often-laborious process produced candidates that the Democrats successfully cast as too conservative for Virginia in an election in which Republicans lost all three statewide seats on the November ballot.

The Koch-backed Americans for Prosperity will host a party Friday night, and American Crossroads, which Gillespie helped found with Rove, hasn’t ruled out jumping into the race.

“American Crossroads does not make it a practice to announce our involvement in races in advance. With that said, Ed has built a strong campaign that has made this race competitive in a swing state and we’re monitoring it closely,” spokesman Paul Lindsay said.

Gillespie has raised nearly $3 million, and had $2.3 million to spend three weeks before the convention. Compare that to the more than $12.5 million Warner has raised. And in addition to the $9.4 million cash on hand, he boasts a personal fortune amassed investing in the cellphone company that became Nextel.

Early polling puts him comfortably ahead of Gillespie. The latest poll, a Quinnipiac survey taken in March, put Warner 15 points up, while just 49 percent said he deserved reelection.

Millions of dollars will flow to ads debating the health-care law. Gillespie wants to repeal and replace, but he’s not saying just yet what he’d support. “I will be talking about that in the course of the campaign,” he said.

Rep Robert C. “Bobby” Scott (D-Va.), an 11-term congressman from the Hampton Roads region who has known Warner for more than 20 years, said that wasn’t good enough.

“I’m interested to hear what Mr. Gillespie’s plan is for people with pre-existing conditions, people who couldn’t afford health-care coverage before, women who no longer pay more for insurance than men,” he said.

Warner, meanwhile, is already on TV with positive spots. If he goes on the offense on health care, he has been noncommittal on new emissions regulations that would hit coal and southwest Virginia hard.

Gillespie has so far run an under-the-radar campaign operation, eschewing public events in favor of the small gatherings frequented by the same people who will drive all the way to Roanoke to pick the GOP nominee. On Thursday he broke with that practice to roll out what he called his five-point “agenda for economic growth” on a conference call with reporters.

That’s just fine with Cohen, the Virginia Beach tea party donor, who already feels like he knows Gillespie.

“He was tea party 20 years ago before we even had a tea party movement,” he said, adding: “I know he has some ties with a few unsavory individuals, but you can’t blacklist someone because of who they’ve worked for in the past.”

Gillespie insists that he’s in the race to win it. If that strategy fails, the governor’s race is just three years away.

“Virginia Republicans are big on, ‘It’s my turn,’ ” said Jennifer Duffy of the Cook Political Report. “If he runs a good race and loses but has a respectable showing, he’s first in line.”