US supreme court justice Samuel Alito was reportedly taken to a hospital after becoming sick at a Federalist Society dinner in Philadelphia in March, further fueling speculation that Donald Trump could have more chances to shape the land’s highest court through new appointments.

A CNN report said Alito was checked by medical staff and given fluids due to dehydration. He later returned to his home in Virginia that same night with his security detail. In the weeks since, Alito has resumed his duties, including participating in oral arguments.

The supreme court’s public information officer, Patricia McCabe, confirmed the incident and shared a statement with the Guardian that said, “On the evening of Friday, [20 March], Justice Alito felt ill during an event in Philadelphia. Out of an abundance of caution, he agreed with his security detail’s recommendation to see a physician before the three-hour drive home.”

The statement said: “After that examination and the administration of fluids for dehydration, he returned home that night, as previously planned. Justice Alito was thoroughly checked by his own physician, and he returned to work the following Monday for oral argument.”

Alito, who turned 76 on Wednesday and has served on the court for 20 years, has become the focus of growing discussion among commentators and media outlets across the political spectrum about whether he might step down.

He is widely regarded as one of the most consistently conservative justices on the supreme court. Appointed by then-president George W Bush in 2006, he has often pushed the court to the right on several issues such as abortion and religious freedom, frequently aligning with fellow conservative justice Clarence Thomas.

Much of the attention around Alito’s potential retirement centers on the possibility that it would give Trump the chance to appoint a fourth justice to the nine-member court, probably someone equally or more to the right of Alito – and much younger.

Trump appointed three justices during his first presidency: Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett. Now, progressive groups are preparing for the possibility that both Clarence Thomas, 77, and Samuel Alito, 76, could retire while Trump is in office, giving him the opportunity to further mold the court’s composition.

If the president is able to name two additional justices, it would preserve the court’s current 6-3 conservative balance and potentially create a Trump-aligned majority that could influence decisions for decades.

Demand Justice, a prominent progressive legal advocacy group, is rolling out a multimillion-dollar effort in advance to oppose potential Trump supreme court nominees even before any seats become vacant. The campaign will begin with $3m in funding, with an additional $15m planned if Trump moves forward with nominations to replace Thomas or Alito.

“Democrats must treat the prospect of Trump filling more supreme court vacancies as the grave threat it is,” the president of Demand Justice, Josh Orton, said in a statement. “Trump knows that the court is about raw political power – power to protect himself, power to reward his billionaire allies, and power to enable ICE to intimidate and attack American citizens.

“He is not going to leave office with his most loyal justices in their 80s and hope for the best. He’s going to act, and we’ll be ready.”

The director of nominations and democracy at the National Women’s Law Center, Alison Gill, expressed concern that replacing Alito with a younger, like-minded justice would continue the court’s marked rightwing trajectory. She believes this would allow for an even easier path to undermining rights for women, LGBTQ+ individuals and people of color.

There is also speculation that encouraging the justices into retirement is a strategic way for the most radical of conservatives to garner as much power as possible before Trump leaves office and the right wing continues to lose popularity among the general public. Recent polling from YouGov and the Economist found Trump’s approval rating at 35% as the war in Iran becomes more prolonged.

“Trump has a record of nominating extremist judges who are loyalists above everything else,” Gill said. “There is an election coming up, and everyone knows it’s very possible that the Republicans may not control the Senate after that. I could certainly see there being an effort to make changes while the Republican party is still in control.

She added: “We need a court that upholds the rule of law that provides checks and balances on the president. A court that protects civil rights and that provides equal justice for everyone, and unfortunately, a justice in the same vein as Alito will not get us there.”