Democratic dissenters on the issue of abortion have made their case to the platform committee, arguing that the party should change its language enough to allow for some diversity of opinion on the matter and return to the “big tent” approach of the Clinton years.

The effort is probably doomed; NARAL Pro-Choice America President Nancy Keenan is on the committee, and those pushing for the change were happy just to get to testify; they weren’t even allowed to do that four years ago.

This time around, Janet Robert, who founded Minnesota’s progressive talk-radio station AM950, with talkers such as Ed Schultz and Thom Hartmann, was given seven minutes to make the case, and she used it to argue that the party simply cannot win back Congress without Democrats who differ from the ’08 platform on this one issue. She cited a slew of stats, including a Gallup poll from last year in which 44 percent of Democrats said abortion should only be legal “in a few circumstances.”

The plank they want to rewrite says the party “unequivocally” supports Roe v. Wade and spells out that “we oppose any and all efforts to weaken or undermine that right.”

Robert urged the committee members to prove that Democrats are more tolerant and open-minded than their opponents across the aisle: “Republicans are continually telling people they are unwelcome because of who they are, what they believe or where they were born. We are not that party.”

There’s no question that Democrats won the House in ’06 by running more moderate candidates in districts the party would otherwise have lost to Republicans.

But the abortion-rights lobby writes big checks and wields such unlimited power that I’ve long thought abortion rights have become to the Democrats what the Second Amendment is to Republicans — who are so terrified of the “slippery slope” that even the most common-sense gun restrictions are out of the question.

Another factor is that Democrats no longer see outreach to social moderates — the Blue Dogs, many of whom were turned out of office in ’10 — as the path to regaining a House majority.

This year, the face of Democratic diversity is a pro-trade, pro-business fiscal conservative running to take back the suburbs.

One House district that both pro-life and pro-choice Democrats see as illustrative in this argument is the Pennsylvania seat previously held by Democrat Kathy Dahlkemper, who opposes abortion rights and won in ’08. She lost in ’10 after antiabortion activists on the Republican side presented her vote for the Affordable Care Act as a vote to fund abortions, although the bill explicitly and repeatedly bars such funding.

Her time in the Democratic women’s caucus was pretty lonely, she told me. “Yes, it was a barrier to relationships with some people. There’s so much middle ground, yet because this issue has been used on both sides more for fund raising than policy, the discussion on what we could do doesn’t even happen.”

These days, her district is represented by Republican Mike Kelly, who recently compared the day that the contraceptive mandate kicked in to 9/11 and the day Pearl Harbor was attacked. Redistricting just put that seat out of reach for Democrats, though.

The Democrats who want the platform language changed say greater support for the party’s Kathy Dahlkempers would put many more districts into play, while those who disagree argue that social issues and Blue Dogs are beside the point in this election, and a moot point in Dahlkemper’s now-safely Republican district.

So what response did Robert, who heads the Democrats for Life , get from the platform committee? Well, Barney Frank was nice — wait, did I bury the lede? — and Bob Wexler made some vaguely encouraging remarks. A few “pro-choice insiders” have been encouraging, too, says Catholic University’s Steve Schneck, and a couple of big party names are lending “quiet support.”

So quiet, in fact, that it doesn’t help at all. The draft of the platform comes out Thursday, and until then nobody wants to get a call from NARAL’s Keenan, who through a spokeswoman took a pass on talking to me.

Melinda Henneberger is a Washington Post political writer and anchors the paper’s She the People blog.