WASHINGTON — Pointed questions from Supreme Court justices raised doubts last month about the viability of the health care reform law’s individual mandate.

The skepticism over the mandate, which dictates that everyone obtain health insurance or pay a penalty, emerged during the court’s three days of hearings on the Affordable Care Act’s constitutionality in late March. A decision is expected by late June.

At stake for retail pharmacy are 32 million potential customers that would be brought into the health care system in 2014.

“Can you create commerce in order to regulate it?” Justice Anthony Kennedy asked the Obama administration’s lawyer, Solicitor General Donald Verrilli Jr. “You are changing the relationship of the individual to the government.”

If the mandate is thrown out, the Supreme Court must also decide whether that voids the entire statute. Overturning the entire law would also mean an end to parts of it that have already taken effect — including subsidies for seniors to cover the “doughnut hole” in Medicare Part D prescription drug coverage.

Considering the question of the entire law’s validity, Justice Ruth Bader Ginsburg said the panel was being asked to decide between “a wrecking operation” and “a salvage job.”

“The more conservative approach,” she said, “would be salvage rather than throwing out everything.”

Also considered by the court, in an unusual afternoon session, was a challenge from 26 states to the law’s expansion of Medicaid.

Regardless of the case’s outcome, it is expected to be a central issue in the 2012 elections.

White House officials expressed optimism that the statute would be upheld, stressing that the fall elections are likely to be decided by the state of the economy and not on opposition to or support of health care reform.