The National Organization for Women (NOW) is urging its members to "thank" or "spank" lawmakers for their votes on an anti-abortion bill that passed the House 227-188 on Tuesday.
In an email, the group blasted the measure to withdraw tax benefits from health plans that cover abortion and called on supporters to contact their representatives.
The message and related website repeated the "thank 'em or spank 'em" refrain several times. Each linked to a system that automatically generates a form letter based on a user's congressional district.
Democrats who voted against the GOP measure received thanks in the letters, while Republicans were asked, "How could you?"
The move followed House lawmakers' first anti-abortion vote of 2014, a year that's expected to see women's health issues figure prominently in midterm election debates.
The bill passed Tuesday would broaden and make permanent a longstanding ban on taxpayer funding for abortion.
The measure would prohibit government doctors and facilities from performing abortions, as well as eliminate tax credits for private health plans that cover the procedure.
Exceptions are made in cases of rape, incest and when the woman's life is threatened.
Supporters argue that the bill is necessary to put more distance between taxpayer money and the practice of abortion.
But opponents say the measure will require the Internal Revenue Service to police the origin of terminated pregnancies for tax compliance purposes.
Abortion-rights groups recently coined the term "rape audits" to refer to the possible outcome of the bill, a charge that was echoed in an email from the Democratic Congressional Campaign Committee.
These developments suggest that debates over abortion and contraception could become a hallmark of the 2014 campaign cycle, just as they were in the last election season.
The Republican National Committee is urging its candidates to speak openly about abortion this year while privately instructing them to proceed cautiously when they do so.