Vice President Kamala Harris has forsworn direct donations from lobbyists, but they are welcoming her candidacy and finding other ways to support it.

In the days since President Biden dropped his re-election campaign and Ms. Harris moved swiftly to lock up the Democratic Party’s nomination, Washington’s influence industry has quietly jockeyed to position itself with her team.

Officials at some of the biggest law and lobbying firms have endorsed her presidential campaign and are raising money for it, using loopholes to get around the campaign’s policy of not accepting donations from lobbyists. They have briefed clients about her policy positions, the composition of her inner circle and the pool of possible running mates. Some lobbying firms have highlighted their connections to Ms. Harris, drawing the ire of allies seeking to avoid the perception that she is beholden to special interests.

“Human nature is such that anybody that ever walked past somebody on the street would try to capitalize,” said former Senator Doug Jones, an Alabama Democrat who is close to Ms. Harris. “Especially in a campaign for president, there is always going to be those folks.”

“That’s Washington, isn’t it?” he added.

Mr. Jones — a government relations adviser, but not a registered lobbyist, at the law and lobbying firm Arent Fox — said he was planning a Washington fund-raising event for Ms. Harris’s campaign featuring lawyers from a host of firms.