In a campaign launched Sunday, AJCongress urged people to write, call or e-mail the prominent feminist publication to "register your complaint at their anti-Israel bias."
It also has enlisted the support of high-powered Jewish feminist speakers, several of whom were to appear at a news conference Tuesday.
The ad in question features photos of three prominent Israeli women leaders and the phrase "This is Israel."
AJCongress leaders claim Ms. rejected the ad because of its bias against Israel -- a charge the magazine's executive editor hotly denied.
"We only take mission-driven advertisements," Katherine Spillar said last Friday.
"Because two of the women were from the same political party, we understood it as political endorsement," she said. Ms. "does not get involved in the domestic politics" of other countries.
AJCongress President Richard Gordon called that argument "specious," noting that in any parliamentary democracy, the foreign minister and parliament leader are going to be from the same party.
Gordon also noted that none of the women are running for office, and the ad does not suggest support for either of their parties.
He pointed out that Ms. ran a cover story about Jordan's Queen Noor in 2003, and a story in its most recent issue about Rep. Nancy Pelosi (D-San Francisco), the speaker of the U.S. House of Representatives, under the headline "This is What a Speaker Looks Like."
Gordon said the only difference he sees between Pelosi and the three women featured in the AJCongress ad is that Pelosi is not Israeli.
"Ms. magazine obviously is trying to create a legal fiction after the fact to cover their bias at the time of the incident," he said.
Spillar said Tuesday that it is "unfair and untrue" to allege that Ms. magazine is anti-Israel. She said the magazine is running a two-page profile of Israeli Minister of Foreign Affairs Tzipi Livni, one of the three leaders pictured in the AJCongress ad, in its Winter 2008 issue, which hits newsstands Jan. 29.
In a faxed statement, Spillar wrote that the magazine has covered the Israeli feminist movement and the country's women leaders in 11 articles in its past 16 issues.
But the AJCongress ad was "inconsistent" with the Ms. policy of not being politically partisan, and the slogan "This is Israel" in the ad "implied that women in Israel hold equal positions of power with men," whereas "Israel, like every other country, has far to go to reach equality for women."
Speaking later to JTA by phone, Spillar said she "puts the U.S. in the same category as Israel" in terms of having far to go to achieve full gender equality. But the AJCongress ad "was almost a country ad, and we don't take country ads."
Harriet Kurlander, the director of AJCongress's Commission for Women's Empowerment, said that when she originally tried to place the ad, a magazine representative told her that the magazine "would love to have an ad from you on women's empowerment, or reproductive freedom, but not on this."
In other conversations with magazine staff members, Kurlander said she was told that publishing the ad would "set off a firestorm."
Kurlander said the magazine should admit its "cover-up" and "simply print the ad."
Among the Jewish feminists speaking out on the issue is Blu Greenberg, the founding president of the Jewish Orthodox Feminist Alliance. Greenberg said that by not accepting the ad, Ms. is "aligning itself with the political far left that wants to delegitimize Israel altogether on the stage of world opinion."
"I wish I could believe that we're overblowing it, but I've been in numerous situations where I've seen the same thing -- this total excoriation of Israel," she said. "That's what we're all feeling right now."
Susan Weidman Schneider of Lilith magazine said she was "very surprised" by the refusal of Ms. to run the ad. But Schneider said that after speaking to the magazine's publisher Monday, she believes the ad was likely rejected "out of a place of ignorance" and was not intended as "a willful slap in the face to Israel."
Weidman Schneider said she considers Spillar's argument "possibly an ex post facto explanation."
She said she told publisher Eleanor Smeal that in retrospect, Ms. would have done better to suggest to the AJCongress that the group shape an ad reflecting a broader range of women's advancement in Israel if any perceived partisanship in the original ad was the impediment.
But beyond the fracas surrounding the actual ad, Weidman Schneider said she is disturbed by the "vitriol" she has seen on Jewish and feminist blogs over the past few days relating to the incident.
"I didn't expect the depth of anti-feminist sentiment that this incident has stirred up," she said, noting that she has read comments referring to "femiNazis" and others suggesting the feminist movement is inherently anti-Israel. "I felt quite chilled."