Russ Feingold, the Democratic senate candidate challenging Wisconsin Sen. Ron Johnson (R.), has accepted $700,000 in contributions bundled by lobbyists this election cycle.

Recent documents filed with the Federal Election Commission by Feingold's campaign committee show that the former Wisconsin senator has added another $210,000 in bundled lobbyist contributions since the beginning of July. These bundled contributions came from three left-wing groups that have supplied a constant flow of cash to Feingold's campaign.

The J Street PAC, a liberal Middle East advocacy group critical of Israel, announced earlier this year that Johnson was one of its primary targets for the 2016 elections.

J Street was one of the biggest backers of President Obama's nuclear deal with Iran, spending millions of dollars on a public relations blitz supporting the deal and lobbying on its behalf in the Senate. Lobbyists from J Street have poured $56,740.97 into Feingold's campaign since July 1.

Lobbyists for the Council for a Livable World, which seeks to eliminate the United States' arsenal of nuclear weapons, contributed $26,440.34 to Feingold's campaign during that period.

Lobbyists from the League of Conservation Voters Action Fund, an environmental advocacy group, contributed $126,777.32 since the beginning of July.

Feingold has now surpassed $700,000 in bundled lobbyist contributions this election cycle, primarily from those three groups. Johnson's campaign does not show any bundled contributions from lobbyists, according to FEC filings.

During Feingold's 18-year stint in the U.S. Senate, he positioned himself on the forefront of campaign finance reform battles that included stricter disclosures from lobbyist bundlers.

"The public voted for change last November in part because it was sick and tired of the way Washington works. The final lobbying and ethics reform bill that Congress will consider this week is landmark legislation," Feingold said in 2007. "It includes a strong lobbyist gift ban, tough new restrictions on privately funded travel and corporate jet flights, much needed additional disclosure of lobbying activities, unprecedented new disclosure of all of the ways that lobbyists provide financial support to members of Congress, including bundling campaign contributions, a provision to slow the revolving door between the halls of Congress and the lobbying world, and far-reaching earmark reform."

Later, Feingold said that politicians should put the interests of their constituents before those of specials interests.

"Regardless of how reforms might impact us, our priority must be to convince our constituents that we are here to advocate their best interests, not those of well-connected lobbyists," he said in August 2007. "Ethical conduct in government should be more than an aspiration. It should be a requirement."

This election is not the first time Feingold has accepted lobbyist cash while railing against the influence of lobbyists. Feingold quietly accepted $200,000 in bundled lobbyist contributions before he was defeated by Johnson in 2010. He has also held numerous fundraisers at venues in Washington, D.C., where he said lobbyists go to buy influence.

Feingold's campaign did not return a request for comment.