In October 2009, I attended J Street’s first national conference in Washington, D.C. The advocacy group, which described itself as a “political home for pro-Israel, pro-peace Americans,” was a year old and already under attack by the American Israel Public Affairs Committee, for half a century the dominant Israel-issues organization.

AIPAC was leaning on members of Congress who had signed up for the conference, leading some to request that their names be withdrawn.

Congresswoman Jan Schakowsky, a Democrat from Illinois, told me she had received a number of calls urging her to steer clear of the conference. Another Democratic House member, who asked not to be named, told me he had been the target of an AIPAC campaign to dissuade him from attending the conference.

J Street was working to convince senators that the sanctions included in the act would undermine, if not end, the Obama administration’s diplomatic engagement with Tehran.

The following weekend, NPR’s Jacki Lyden interviewed J Street founder and president Jeremy Ben-Ami. “AIPAC has tens of millions of dollars and is very influential with a lot of Congress people, several of whom backed out of their invitations after saying they were going to come to your conference,” Lyden said. “You have just several million. Do you think you can deliver?”

Four years later, J Street delivered, countering an AIPAC campaign to push an Iran sanctions bill through the Senate, thus allowing President Obama time to make his case. Going into the State of the Union, 59 senators, including 16 Democrats, were supporting a bill that would have derailed diplomatic efforts intended to persuade Tehran to give up its pursuit of nuclear weapons.

AIPAC wasn’t speaking for the record, but Illinois Republican Senator Mark Kirk told the National Journal that AIPAC’s campaign included regular briefings from the advocacy group’s leadership regarding the Nuclear Weapon Free Iran Act.

At the same time, J Street was working to convince senators that the sanctions included in the act would undermine, if not end, the Obama administration’s diplomatic engagement with Tehran.

J Street was not without allies. In 2012, J Street’s PAC had endorsed California Senator Dianne Feinstein—“one of its biggest names,” The New York Times reported—committing to raise $100,000 for her campaign.

J Street ended up contributing $82,781 to Feinstein’s campaign (only $20,000 less than Pacific Gas & Electric). Did J Street move Feinstein to a more moderate position or was she already there and eager to accept the support? The answer probably is more nuanced than the question, but two years later Feinstein was the critical voice at a critical moment in the debate about the Iran sanctions act.

Because she chairs the Senate Intelligence Committee and has been unflagging in her support for Israel, Feinstein’s vocal opposition to the sanctions act resonated with Senate Democrats, keeping the tally of supporters below 66, which would have almost ensured passage. None of the seven Democrats endorsed by J Street joined the 16 Senate Democrats supporting the act.

By February, four Democratic Senators who had supported the sanctions act had withdrawn support, including Connecticut’s Richard Blumenthal who had been a co-sponsor. And Hillary Clinton, whose future support among progressives hinged on her position on the Iran sanctions act, according to Spectator blogger M.J. Rosenberg, announced that she opposed it.

The fight over the sanctions bill was a rite of passage for an organization that Ben-Ami started in his basement in 2007. (It helped that he had worked as an advisor in the Clinton administration.)

While it’s far too early to write AIPAC’s obituary, in early February the Times’ Mark Lander described the Iran sanctions fight as the end of AIPAC’s “impressive record of legislative victories in its quest for American support for Israel.” J Street had, as a Congressional aide told the National Journal, “broadened the definition, the boundaries, of what it means to be pro-Israel.”

As we go to press, more than 90 House Democrats have signed onto a letter opposing any sanctions bill while the Obama administration is negotiating with Iran. The letter was written by Texas Democrat Lloyd Doggett who had been supported and endorsed by J Street.

Lou Dubose is the editor of The Washington Spectator.