WASHINGTON — Jim Johnson, the most experienced hand guiding Democrat Barack Obama's vice-presidential search, stepped down Wednesday as Republican criticism of his home mortgage deals became a distraction for a candidate who eschews Washington insider influence.

Johnson's resignation leaves the job of vetting Obama's No. 2 at least temporarily in the hands of two other prominent Democratic attorneys who had been working with him on the search: former deputy attorney general Eric Holder and Caroline Kennedy, daughter of late president John Kennedy.

The Obama campaign declined to answer whether the Illinois senator would replace Johnson, who also led the vetting for Democratic nominees John Kerry in 2004 and Walter Mondale in 1984. Obama said in a statement that he was grateful to Johnson for his service.

"Jim did not want to distract in any way from the very important task of gathering information about my vice-presidential nominee, so he has made a decision to step aside that I accept,'' Obama said. "We have a very good selection process underway, and I am confident that it will produce a number of highly qualified candidates for me to choose from in the weeks ahead.''

Johnson, the former chairman of mortgage lender Fannie Mae, came under fire from Republican candidate John McCain and the Republican party after The Wall Street Journal reported last Saturday that Johnson got mortgage loans with help from the CEO of Countrywide Financial Corp.

McCain had accused Obama of hypocrisy for speaking out against Countrywide's role in the subprime mortgage crisis.

Johnson's resignation allows Obama to move on with the vetting process without the criticism surrounding him, but it also could make it appear that the campaign quickly caved under pressure. The resignation touched off a series of accusations between the two campaigns about which candidate has more tainted advisers and better judgment about who to surround himself with.

Obama's campaign has had varying responses when controversy has focused on those around him. Foreign policy adviser Samantha Power left within hours of calling Hillary Rodham Clinton a "monster.'' Obama was initially reluctant to disavow his pastor, Jeremiah Wright, after video of racially explosive sermons emerged. And he kept leading economic adviser Austan Goolsbee on board amid controversy surrounding his private comments on free trade.

At least five McCain staffers have left his campaign in the wake of a Democratic uproar over McCain's connections to lobbyists. McCain responded by banning registered lobbyists serving his campaign but has defended two of his top advisers -- Rick Davis and Charlie Black -- who left their lobbying jobs to work for his presidential bid.

Johnson and Holder had been holding meetings this week with lawmakers on Capitol Hill to seek their input on possible running mate candidates.