Updated

Two left-leaning groups that came under fire in December for using the disparaging term "Israel firster" in their Middle East commentary have taken sharply different paths to address the complaints.

The Center for American Progress has denounced the term and instituted "oversight" changes -- while the staffer who used "Israel firster" on his Twitter account apologized, deleted the tweets and has since left CAP for another group.

But Media Matters For America seemingly has not cracked down on its senior fellow, MJ Rosenberg, who continues to throw around and defend the controversial term on his Twitter page.

The Simon Wiesenthal Center, arguably the toughest critic of those using the term, reported Wednesday that -- at least at CAP -- changes have been made.

"I think that the people who run CAP, I think they got the message," said Rabbi Abraham Cooper, associate dean at the California-based Jewish rights group.

"We're not the thought police ... but we know a lot about anti-Semitism," he told FoxNews.com. "And that kind of shorthand could be deadly."

The "Israel firster" term is used to describe lawmakers and others who voice unwavering support for Israel, but it also implies that their loyalties are to Israel first, and to America second.

Cooper said he brought up the issue last month during a previously scheduled meeting at the White House with the recently appointed Jewish liaison.

Cooper said the liaison, Jarrod Bernstein, immediately assured Cooper that the White House did not condone that language. "He said something to the effect of, 'we're also very troubled by it,'" he said, calling the reaction "definitive."

Cooper said he hasn't noticed inflammatory terms used by CAP writers in recent weeks.

"The main reason I spoke up is I wanted to make sure everybody understands how laden a term like Israel firster was," Cooper said. "Part of this is generational, part of it is not really understanding (the impact) of the blog term that's thrown out there."

He suggested, for instance, that reducing the debate over Iran's nuclear program to a question of whether those warning about it are "Israel firsters" would be "disastrous."

The Anti-Defamation League also said in a written statement that the Center for American Progress "took the matter seriously and understood the anti-Semitic nature of raising dual-loyalty canards."

According to the statement, CAP assured the ADL that they instituted "new oversight procedures in the aftermath of the controversy and made sure terms like 'Israel-firster' were deleted from the Twitter accounts of CAP staffers where they appeared."

The ADL praised CAP for taking "concrete steps" to address the problem.

The Center for American Progress said in an earlier statement that it has a "zero-tolerance policy on anti-Semitism."

"A very small number of tweets on the personal accounts of ThinkProgress staff were inappropriate, and the authors have publicly apologized for using objectionable language. That language never appeared in any CAP or ThinkProgress publication, and we have taken steps to ensure that all CAP staff maintain the highest standards in their communications even in their personal social media accounts," the organization said, adding that the group is "pro-Israel" and supportive of a two-state solution, as the "overwhelming record from hundreds of our articles, posts, and policy papers demonstrates."

But Rosenberg has made a point of not backing down. While his most recent columns on Huffington Post and the Media Matters website mostly center on the rhetoric being employed with regard to Iran's nuclear program, his Twitter page routinely returns to the issue of the "Israel firster" term.

"'Israel Firster' debate is an American argument, not a Jewish argument," he tweeted Monday, in reference to a blog that suggested the debate over the term is "wide open."

Rosenberg, who used to work at the American Israel Public Affairs Committee, has argued that he is pro-Israel and only using the "firster" term to describe people who put the interests of the Benjamin Netanyahu administration -- whom he describes as "hardliners" -- first.

"The neocons are exposing my 40 year career as a pro-Israel advocate. I was then. I am now. My standing on issue is impeccable. Theirs?" Rosenberg wrote Monday on Twitter.

Apparently under pressure, he briefly threatened to shut down his Twitter page to avoid "psycho pests."

He then backtracked.

"Never mind. I'm not quitting. Deluged my supporters who worry that they wont see Israel Firster term anymore. Not to worry," he tweeted on Wednesday.

The controversy erupted two months ago as Josh Block, a former spokesman for AIPAC, provided the media with a raft of complaints about the Center for American Progress' coverage.

Those complaints gained traction, and CAP writers were put under the microscope for a string of columns for the affiliated Think Progress blog and comments on Twitter. One writer compared the "siege" in the Gaza Strip to "segregation in the American South." Another claimed AIPAC was banging the war drums on Iran. Another decried the Simon Wiesenthal Center as a "far-right" organization that "basically called Obama a Nazi" when it criticized the president for backing a return to Israel's 1967 borders.

As Block's complaints gained traction, the Simon Wiesenthal Center spoke out, saying the "sponsored bloggers are guilty of dangerous political libels resonating with historic and toxic anti-Jewish prejudices."

The Think Progress blogger who used the "Israel firster" term on his Twitter page, Zaid Jilani, later left the group and joined United Republic.

The Jerusalem Post reported last month that the editor of Think Progress acknowledged in an email that the term was "terrible, anti-Semitic language." The editor, according to the Post, wrote that Jilani "also knows and understands the implications."

A representative with Media Matters did not return a request for comment by FoxNews.com.