Rep. Gary Palmer (R-Ala.) (MARK ALMOND/AP)

Advocates on both sides of the abortion debate warned House members that they will closely monitor votes on a measure to block a District law that says employers cannot discriminate against workers based on their reproductive health decisions.

Rep. Gary Palmer (R-Ala.) last month filed an amendment to the House appropriations bill for fiscal year 2018, to prevent the District from using funds to carry out the Reproductive Health Non-Discrimination Amendment Act.

The House is expected to pass the measure late Wednesday, but it must still clear the Senate and be signed by President Trump before it can take effect.

Planned Parenthood Federation of America and NARAL Pro-Choice America — as well as the American Civil Liberties Union and Americans United for Separation of Church and State — urged lawmakers to oppose Palmer's amendment.

Heritage Action, the political arm of the Heritage Foundation, and Concerned Women for America, which are opposed to abortion rights, urged members to support it.

Groups on the left and right warned lawmakers that they will closely track how members vote and grade them.

Del. Eleanor Holmes Norton (D), the District's nonvoting representative, said she will fight Palmer's amendment on the floor, but has said D.C. officials rely on the Senate as a backstop for efforts to overrule city laws.

The law bans employers from taking action against workers based on their decision to use birth control or seek an abortion.

In an alert to lawmakers, Planned Parenthood said the Palmer amendment is in keeping with bills moved in state legislatures that would protect businesses that discriminate against employees or deny services to customers based on their religious beliefs.

"The Palmer amendment represents a broader agenda by anti-women's health and anti-LGBT leaders in the House to roll back access to care and services," according to a letter from the organization's political arm.

Some conservatives and Catholic groups initially interpreted the city law to mean that employers in the District, including churches and antiabortion groups such as March for Life, could be forced to provide coverage for contraception and abortions.

The city council later clarified that the law should not be used "to require an employer to provide insurance coverage related to a reproductive health decision."

Heritage, which favors the Palmer amendment, said the law is still problematic because it could force employers opposed to abortion to hire employees who openly support abortion rights, infringing on the employers' right of free association.

"Failure to act on [the D.C. law] would further embolden D.C. city council's extreme political agenda, which continues to threaten pro-life organizations based in the District of Columbia and the religious liberty of all Americans," according to a Heritage statement.

The law has survived two previous attempts to squash it from Republican members.

In 2015, shortly after the city council passed the law, the House voted along party lines to kill it, but the Senate never adopted the measure.

The following year, Palmer tried to block funding for its implementation. The House passed the amendment, but it never reached the Senate floor.