A long list of conservative leaders is imploring congressional Republicans to halt the movement of appropriations lacking a decades-old provision that blocks federal funding of most abortions.

"We urge all conservatives, and anyone who values the sanctity and dignity of human life from conception until natural death, to oppose spending legislation which does not contain the Hyde amendment and key related pro-life policies," reads a letter from more than 100 conservative leaders, activists and former legislators. 

Sent to GOP lawmakers in both chambers, Tuesday's letter signals the movement's attempt to fortify a Republican defense after Democrats approved appropriations bills without Hyde. 

For decades, both parties supported the amendment as a compromise amid expanded abortion access. Polling has also tended to show Americans oppose taxpayer funding of abortion. 

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But the political climate has shifted since the 2020 presidential primaries, when then-candidate Joe Biden reversed his decadeslong support for the measure amid pressure from the Democratic field. 

"Over decades, both Democrat and Republican presidents have signed these protections into law – protections that were, for years, supported by President Biden in the United States Senate," reads Tuesday's letter.

"But despite the broad bipartisan consensus and the national federal support for these policies, House Democrats have for the first time passed spending bills without them, raising the possibility that millions of Americans who are deeply and profoundly opposed to abortion will find their tax dollars used to subsidize the practice." 

The signatories included an array of prominent conservatives, including former Sen. Jim DeMint, R-S.C., former Office of Management and Budget Director Russ Vought and former Trump adviser David Bossie. Heavy-hitters in the anti-abortion movement – Susan B. Anthony List's Marjorie Dannenfelser, Concerned Women for America's Penny Young Nance and March for Life's Tom McClusky -- signed on as well.

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The unprecedented move by Democrats has once again magnified the high-stakes nature of current partisan division in Congress. Democrats, with a slim majority in the House, will need to garner 60 votes to pass a budget without Hyde in the Senate. 

Given that Republicans comprise half the chamber, conservatives have worried that progressives might resort to ending the filibuster in order ensure Hyde and other anti-abortion measures don't pass under a newly elected Democratic president. Still, the party would have to overcome the influence of moderate Democrats like Sen. Joe Manchin, D-W.Va., who has opposed both Hyde's removal and ending the filibuster. 

Senate Minority Leader Mitch McConnell, R-Ky., has already made clear that his party would oppose Hyde's removal, describing the move as an indication of how far left the Democratic party has drifted in recent years.

Even without necessary votes, progressives aren't likely to back down easily since they often frame low-income abortion access as a moral imperative. 

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"Your ZIP code, income, or the type of health insurance you have should never determine what kind of essential health care services you can access," Planned Parenthood CEO Alexis McGill Johnson said in a press release this week.  

"It’s past time for Congress to remove these racist, discriminatory barriers to abortion care from our federal laws," she continued.

Both sides have warred over the racial aspect of abortion as minorities are disproportionately represented among mothers who obtain the procedure.

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Conservatives see Hyde as a life-or-death issue, citing estimates for how many lives they say were saved by the funding restriction.  

"The Hyde amendment and its related policies are estimated to have saved the lives of 2.4 million babies since its inception," read Tuesday's letter. The signatories appeared to reference an estimate earlier this year by the anti-abortion Charlotte Lozier Institute.