Were he to run for the U.S. Senate in Virginia, Republican Ed Gillespie would be as emphatically critical of the federal health care law as most other GOP candidates -- but he would first need to reconcile his past positions on the issue.

Gillespie, a former mega-lobbyist and chairman of the Republican National Committee, is weighing a challenge to Sen. Mark Warner, D-Va., a popular incumbent.

Health care is expected to be an issue in many 2014 congressional contests, including Virginia, and Gillespie's record on the issue is likely to make him a ripe target for Democrats -- or Republican primary challengers.

In 2007, Gillespie was lobbying on behalf of a group advocating health care reform, including a push for universal coverage, something Republicans have since denounced. The connection became an issue in the 2012 presidential contest when Gillespie was an adviser to Republican nominee Mitt Romney.

“If I run against Sen. Warner, my critique of Obamacare will be consistent with my past positions in opposition to an individual mandate and too much government intrusion in our health care sector,” Gillespie told the Washington Examiner Wednesday.

The issue could become a difficult obstacle for Gillespie should Virginia Republicans opt to nominate its 2014 candidates in a convention rather than an open primary, as it did this year. Republican conventions, often dominated by conservatives, tend to favor nominees who skew further right.

Gillespie was working as a lobbyist for the Coalition to Advance Healthcare Reform, which promoted "market-based reforms" of the nation's health care system. Those reforms, the group said in a 2007 statement, were designed to create a “Market-Based Healthcare System; Universal Coverage with Individual Responsibility; Financial Assistance for Low-Income Individuals; Healthier Behavior and Incentives; Equal Tax Treatment.”

Gillespie said his work on behalf of the coalition didn't include direct lobby in support of an individual mandate, which requires everyone to buy health insurance and is now a central element of Obamacare.

“Throughout the debate on Obamacare I strongly criticized the mandate, and in my own book I talk about market-based reforms as [the] best approach,” Gillespie said.

In Gillespie’s 2006 book, “Winning Right,” he enumerates five tenets to “ensure that efficiency, affordability, and availability would prevail in the health care sector.” The fifth principle was “all adults participate.”

Gillespie proposed ensuring "that every emancipated adult capable of providing for his or her health care do so. One way to accomplish this is to use the tax code to gain compliance.”

The goal of this, as with the mandate in the federal health care law now in place, was to reduce insurance costs across the board.

Some of Gillespie’s other proposals from his book also sound familiar, either because they are similar to the health care law Mitt Romney crafted when he was governor of Massachusetts or because they have been incorporated into the federal health care law, including a system anchored in insurance exchanges with “portable” coverage.

Gillespie isn't the only Republican who once embraced — but now derides —some of those free-market reforms. The seminal idea for market-based, comprehensive reform to the nation’s healthcare system, including an individual mandate, was first pitched in 1989 by the conservative Heritage Foundation and its allies.

Gillespie now strikes a tone more in line with the current Republican message on health care, as he did in 2009 when he told George Stephanopoulos of ABC News.

“This bill is a monstrosity," Gillespie said, "and from a Republican perspective, if you look at the mandates in it, the taxes in it, the cutting of Medicare for seniors, the federal funding of abortion, I feel like it's one of those old game shows where you take the shopping cart down the aisle and try to scoop it all in, in terms of trying to pick out where do you hone in on all this."

There is also a lingering question of how Gillespie would frame issues such as healthcare and immigration reform were he to run for Senate, particularly in light of research his own firm conducted into such messaging.

Gillespie was until last year a founding board member of the Republican group Resurgent Republic, which, among other projects, researched voter sentiment and reaction to policy objectives and then made recommendations on how GOP candidates should discuss those issues.

The group concluded in a May 2010 memo that Republicans would be better off talking about health care and immigration in more nuanced terms, like recommending changes to the health care law rather than demanding its full repeal. Candidates were also told to say "legalization" rather than "amnesty" in debates over immigration.

But Gillespie said those findings would not affect the way he would campaign were he to run for the Senate.

“Testing messages, including liberal messages, does not mean agreeing with them,” Gillespie said when asked about the firm’s findings. The firm, he added, “releases the results from all questions asked, even results we don’t always like to see but that conservatives should be aware of when it comes to public perceptions.”

Gillespie will need to decide whether to challenge Warner before Virginia's Feb. 1 filing deadline. He said earlier this month that he's been hearing from “many friends from across Virginia urging me to run.”

But Warner, who until now was seen as a shoo-in for re-election, would be a formidable competitor. The former Virginia governor is solidly popular at home, with approval ratings around 60 percent, and he has already raised nearly $6 million in campaign cash.