WASHINGTON (CNN) -- The day after Jim Johnson resigned from Sen. Barack Obama's vice presidential candidate vetting committee, Sen. John McCain set his sights on Eric Holder, one of the two remaining members of the committee.

Sen. John McCain on Thursday critized Eric Holder for his recommendations about a commodities trader.

"I think people in the media and observers will make a decision as to whether these people, individuals, should be part of Sen. Obama's campaign," McCain said in Boston, Massachusetts, on Thursday. "I think it is a matter of record that Mr. Holder recommended the pardoning of Mr. [Marc] Rich."

Rich was a commodities trader who fled to Europe in 1983 after tax evasion charges and allegations of illegal oil dealings with Iran. He was pardoned by former President Clinton at the end of his second term, while Holder was deputy attorney general.

In a response Thursday, Obama campaign spokesman Hari Sevugan said McCain was raising old allegations rather than talking about the issues.

"It's telling that John McCain -- whose vice presidential search process is headed by a prominent D.C. lobbyist who served as the Reagan administration's point man on the Iran-Contra scandal -- would try to recycle a tired attack on Mr. Holder," she said.

Sevugan was referring to A.B. Culvahouse, who is leading McCain's vice presidential candidate search and was counsel to the president in the Reagan White House.

Johnson stepped aside Wednesday amid criticism that he received a favorable mortgage from Countrywide Financial, a company that Obama routinely attacks on the stump.

Johnson, a former CEO of Fannie Mae, was one of three people on Obama's search team, alongside Holder and Caroline Kennedy, daughter of President Kennedy. Watch more on Johnson stepping down »

"All those things will be taken into consideration by the media and the American people, especially when you are entrusting individuals with one of the most important decisions that a presidential candidate can make before that individual is elected, and that is who the running mate is," McCain added. Watch McCain react to Johnson resignation, take aim at Holder »

Following criticism by the McCain camp after Johnson stepped down, Obama spokesman Bill Burton quickly responded, pointing to two of McCain's top advisers, including Culvahouse.

"We don't need any lectures from a campaign that waited 15 months to purge the lobbyists from their staff, and only did so because they said it was a 'perception problem,' " Burton said in an e-mail.

"It's too bad their campaign is still rife with lobbyist influence and doesn't see a similar 'perception problem' with the man currently running their own vice presidential selection process, a prominent D.C. lobbyist whose firm has represented Exxon and a top Enron executive, or their campaign chair and John McCain's top economic adviser Carly Fiorina, who presided over thousands of layoffs at Hewlett Packard while receiving a $21 million severance package and $650,000 in mortgage assistance," he added.

Meanwhile, with the presidential campaigns' vice presidential search teams under scrutiny for ties to special interest groups and lobbying firms, some in Washington say it's hard to find qualified aides detached from business dealings.

Steve McMahon, a Democratic analyst and former adviser for Howard Dean's 2004 presidential campaign, said Thursday that perception that campaigns are void of special interests and lobbying ties are "at the heart of the problem."

"Both campaigns, which have made it a priority to distance themselves from special interest groups and lobbyists, may not be so detached from Beltway insiders," he said. "People inside the Beltway have histories. ... There aren't very many people in this town who do politics exclusively for a living." Watch more of McMahon's interview »

McMahon added that campaign advisers "have other jobs and do other things. If you want to get experienced people in your campaign, you're going to have this challenge. ... But certainly, this idea of running clean campaigns that are free of special interests does set up this contradiction when you look at some of the people they have to hire."

It's a point that David Gergen, a former Clinton administration official and current CNN senior political analyst, agrees with.

"You know, if we're going to take everybody who has commercial ties on either side of the campaign and question anything, any little cloud or any little suspicion and force them out of the politics, I must tell you, we're going to take an awful lot of talent out of politics. And the country will not be better off."

Marcus Mabry, of The New York Times, adds that the problem "isn't Washington."

"People go from these jobs in government to jobs in the private sector all the time," he said. "Some of those jobs are lobbyists. We're not even talking about a lobbyist problem here. We're talking about taking a loan."

Gergen says the fallout from the resignation has been a "blow for the Obama campaign, a major distraction."

"It hit them just at the time they were trying to get traction. They were trying to get some momentum built around the economy, and here they now get diverted over this other issue. And it sort of takes some of the glow off."

For several days, Obama pushed back against the attacks on Johnson, the first person he named to head his search team.

Republican Party spokesman Alex Conant called Obama "naive" and "hypocritical" after Obama's remarks Tuesday, before Johnson stepped down. McCain's campaign ramped up that notion after Johnson's resignation.

Tucker Bounds, a spokesman for the presumed GOP presidential nominee, said Johnson's resignation "raises serious questions about Barack Obama's judgment."

CNN political producer Alexander Marquardt contributed to this report.

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