Updated at 4:06 p.m.

Thirty-nine Republican U.S. Senators on Thursday asked the U.S. Supreme Court to reconsider its abortion-rights rulings in two landmark cases, as the justices prepare in March to weigh whether a Louisiana law regulating reproductive services imposes an "undue burden" on women.

The amicus brief, filed by Americans United for Life, was among more than two dozen that asked the justices to uphold a federal appeals court ruling supporting the Louisiana law. More than 160 members of the U.S. House signed the brief with the Senate Republicans. Thirty-six Senate Democrats, represented by Stroock & Stroock & Lavan, last month submitted a brief backing the Supreme Court's abortion rights rulings in the cases Roe v. Wade and Planned Parenthood v. Casey.

Abortion rights advocates and their counterparts have filed collectively more than 50 amicus briefs over the past several weeks, representing legal scholars, the voices of women, religious groups, medical professionals and others in the one of the term's most closely watched cases. The justices are set to hear the case June Medical Services v. Gee on March 4, evaluating the merits of the law and whether the challengers have legal "standing" to sue in the first place.

The Louisiana law at the center of the case, arriving from the U.S. Court of Appeals for the Fifth Circuit, requires doctors performing abortions to have hospital admitting privileges within 30 miles. The law, earlier blocked by the Supreme Court, mirrors one that the Supreme Court in 2016 upheld in the case Whole Woman's Health v. Hellerstedt. Then-Justice Anthony Kennedy, who has since retired, was in the majority that struck down the Texas law.

"Now with Justices Neil M. Gorsuch and Brett M. Kavanaugh, it is widely thought that there are five votes to allow much more government regulation of abortion and, perhaps, even to overrule Roe v. Wade," Erwin Chemerinsky, dean of University of California at Berkeley School of Law, wrote Thursday at the ABA Journal. Chemerinsky was among the constitutional law scholars who filed a brief last month in the Louisiana case asking the justices to overturn the Fifth Circuit's ruling.

Other amicus briefs asking the court to broadly uphold abortion rights included one that featured personal statements from female lawyers and law students; reproductive rights scholars; the American Bar Association; and Whole Woman's Health. Major U.S. law firms filed most of the pro-abortion rights briefs. By contrast, the amicus briefs backing Louisiana, which were filed over the past several days, primarily featured in-house lawyers, small firms and solo practitioners.

Here's a brief look at some of the filings that support Louisiana:

>> 39 Republican Senators and 168 members of the House: "Amici respectfully suggest that the Fifth Circuit's struggle to define the appropriate 'large fraction' or determine what 'burden' on abortion access is 'undue' illustrates the unworkability of the 'right to abortion' found in Roe v. Wade and the need for the court to again take up the issue of whether Roe and Casey should be reconsidered and, if appropriate, overruled," Steven Aden, chief legal officer and general counsel of Americans United for Life, wrote. Americans United for Life senior counsel Clarke Forsythe separately filed a brief for the group itself. "Roe remains unsettled 47 years after it was decided. The original decision in Roe was divided, and most abortion decisions since then have been closely divided," Forsythe wrote.

>> Louisiana state legislators: "Petitioners want to use women's abortion rights to strike down a law that safeguards those same women during abortion procedures. It is akin to a car manufacturer that hijacks consumer rights to invalidate a regulation that makes cars safer. The Court should reject a third-party standing doctrine that forces this Court to decide important issues based on advocacy from plaintiffs whose interests conflict with those they purport to represent," John Bursch of Alliance Defending Freedom wrote.

Ken Starr Former federal appeals judge Kenneth Starr. Photo: John Disney/ ALM

>> Thomas More Society: "When abortion providers challenge laws that burden their practice, it is questionable whether they are acting on behalf of their patients, or merely acting in their own self-interest," Timothy Newton of the Columbia, South Carolina, firm Murphy & Grantland. The brief also argued: "Nothing is hindering women seeking abortions from bringing their own challenges to Louisiana's statute." Former Judge Kenneth Starr of the U.S. Court of Appeals for the D.C. Circuit appeared as additional counsel on the brief.

>> State of Texas: "To be sure, the court need not overrule anything to rule for the state defendant. The Fifth Circuit correctly demonstrated that the factual record in this case requires upholding Louisiana's law even under Hellerstedt's faulty reasoning. Nevertheless, Texas submits that the better course is to correct errors when they are apparent—especially those as pernicious as Singleton and Hellerstedt. Rather than permit these problems to fester any longer, the court should eliminate their origin," Kyle Hawkins, the Texas solicitor general, wrote. Separately, Nicholas Bronni, solicitor general for Arkansas, filed a brief Thursday for states including Georgia, Florida, South Carolina and Tennessee backing Louisiana.

>> National Right to Life Committee: "Given the [Whole Woman's Health] confusion,this court should clarify that its undue-burden test is a lowered-scrutiny, deferential test that keeps federal courts out of the medical board role," James Bopp Jr. of the Bopp Law Firm wrote.