When the Supreme Court declined late Wednesday to block a severely restrictive Texas abortion law, it was fulfilling the long-held ambitions of a series of committed Republican presidents, senators and conservative activists who worked unceasingly for years to cement a reliable anti-abortion majority on the court.

The decision confirmed the worst fears of reproductive rights activists, who had long warned that conservatives were moving aggressively to put in place a court majority that would upend abortion rights. And it showed the success of a carefully orchestrated master plan that required deep coordination among the conservative legal community, the White House and the Senate, combined with the willingness of Senator Mitch McConnell of Kentucky to play confirmation hardball.

Mr. McConnell, the court-focused Republican leader, denied one Democratic president the right to fill one Supreme Court seat and then raced to fill another with a G.O.P. nominee before a subsequent Democratic president could. Both decisions transformed the ideological makeup of the court and made this week’s decision possible, with the court facing an opportunity to act more definitively against abortion rights this fall.

“This has been the crux of our political strategy for decades,” said Mallory Quigley, the vice president for communications at the conservative Susan B. Anthony List. “It has been to elect pro-life presidents, pro-life senators and put in these pro-life legislators so they could nominate and confirm pro-life Supreme Court justices.”

Those same justices all declared Roe v. Wade well-established precedent and the law of the land during their hearings before the Senate Judiciary Committee, in a time-honored tradition of offering vague euphemisms meant to convey judicial neutrality during their confirmation periods. They promised to keep open minds, testifying that no one involved in their nomination had even asked for their view of the case.

But Democrats were always skeptical, pointing to the conservative backgrounds of the nominees and their strong support from the Federalist Society, a conservative pipeline for federal judges. Opponents now say their deep misgivings are being borne out.

“We warned about it during the confirmation hearings,” said Senator Richard Blumenthal, a Connecticut Democrat who sits on the Judiciary Committee. “We refused to believe the lies from Supreme Court nominees that they would adhere to precedent.”

For Republicans, it was the vindication of a bet made years ago that a focus on the court could help them achieve their policy objectives even if they did not have broad support among the public.

The long-range conservative game plan reached fruition during the administration of Donald J. Trump, who won election in part by promising to put a conservative in the court seat Mr. McConnell left dangling open. Enthusiastically assisted by Mr. McConnell and Senate Republicans, Mr. Trump ended up naming three justices seen as hostile to abortion rights.

Those three, Neil M. Gorsuch, Brett M. Kavanaugh and Amy Coney Barrett, joined with Justices Clarence Thomas and Samuel A. Alito Jr. in declining to block the Texas law widely denounced as violating Supreme Court precedent, putting the court on the precipice of overriding Roe v. Wade.

While the ruling was a win for conservatives, it posed political risks for Republicans and could stir a backlash that energizes Democrats and female voters before the 2022 midterm elections, which will be held after an anticipated court ruling on a second restrictive abortion law in Mississippi.

President Biden assailed the decision as “an unprecedented assault on a woman’s constitutional rights” and promised to initiate a governmentwide review to find ways to maintain access to abortions.

Democratic lawmakers called for Congress to enact legislation codifying guarantees to abortion access. Speaker Nancy Pelosi, labeling the ruling the act of a “radically partisan court,” said the House would vote on such a plan when it returns this month, even though Republicans would almost surely filibuster such a measure in the Senate.

The decision led to renewed calls to expand the Supreme Court to offset the conservative majority that Democrats and progressives say was wrongly installed when Mr. McConnell refused to allow President Barack Obama fill the seat of Antonin Scalia after he died in 2016. The Republican leader then raced to seat Justice Barrett just days before Mr. Biden was elected last year. Mr. Biden has created a commission to study ways to overhaul the court, but has not endorsed a change.

Leaders of the movement say that they still have a ways to go in building the necessary momentum to add seats to the court, but that the abortion decision will aid their efforts as Americans see conservatives and the court realizing their goal of greatly limiting access to abortion.

“This is what they advertised they were going to do, and now they are doing it,” Brian Fallon, the executive director of the progressive group Demand Justice, said about the court. “Now the only question is what are Democrats going to do about it?”

The decision will also intensify calls for broader change in the Senate such as weakening or eliminating the filibuster. Any move to enlarge the court or make other substantial changes to it would most likely require barring the filibuster, as would enacting new voting rights laws that activists say are needed to counter the impact of the conservative court.

Mr. McConnell, recognizing the complex politics surrounding abortion, was reserved in his reaction to the decision despite his hand in reshaping the court.

“I think it was a highly technical decision,” he told reporters at an event in Kentucky on Thursday. “Whether it leads to a broader ruling on Roe vs. Wade is unclear at this point.”

Mr. McConnell’s role in constituting the current court can hardly be overstated. After Justice Scalia’s death in February 2016, Mr. McConnell rallied Senate Republicans to block the nomination of Merrick B. Garland to the seat, saying that openings should not be filled in presidential election years.

The vacancy gave Mr. Trump the chance to attract the support of conservatives wary of him as he openly promised to appoint conservatives he expected to overturn Roe v. Wade, saying it would happen “automatically” when his nominees were seated. Mr. Trump took the unique step of producing a list of potential nominees to further assure conservatives.

After Mr. Trump’s election, he, Mr. McConnell and Donald F. McGahn II, then the White House counsel, aggressively set out to put a heavily conservative imprint on both the Supreme Court and the lower courts.

They started with Justice Gorsuch, who was placed on the court weeks after Mr. Trump took office and Republicans changed Senate rules to prevent Democrats from blocking the nominee through a filibuster. He was followed in 2018 by Justice Kavanaugh, the replacement for Justice Anthony M. Kennedy, who voted repeatedly to uphold abortion rights.

Then, late in 2020 came Justice Barrett, nominated by Mr. Trump to replace Justice Ruth Bader Ginsburg, the abortion rights champion. Despite his protests four years earlier that Supreme Court justices should not be confirmed in presidential election years, Mr. McConnell said that stance applied only when presidents and Senate majorities were of differing parties, as they were in 2016. He hurriedly shepherded Justice Barrett through and she was confirmed in late October, denying Mr. Biden the chance to choose Justice Ginsburg’s replacement.

The confirmation of Justice Barrett was particularly critical since she provided a sixth conservative vote and was considered a hedge against Chief Justice John G. Roberts Jr., who has come to be seen by some conservatives as insufficiently committed to their causes. The chief justice broke with his fellow Republican appointees in dissenting from the Texas decision.

Mr. Blumenthal suggested that while the conservative game plan was succeeding, Republicans might come to regret that it is working as well as it has.

“It is the culmination of years of calculated strategy and manipulation, but it is really explosive for the court,” he said. “The court just sort of lit the house on fire.”