The fundraising chairman for John McCain, the Republican presidential candidate, resigned on Sunday because of his work as a corporate and foreign government lobbyist.

Thomas Loeffler, an attorney and lobbyist whose Texas firm, the Loeffler Group, represents clients ranging from EADS North America to the South Korean government, stepped down just days after the McCain campaign instituted a new policy forbidding any person working for his campaign to be a registered lobbyist. He was the fourth senior official to step down from Mr McCain’s campaign in two weeks.