– U.S. Supreme Court justices hinted Tuesday they might revive one of President Obama’s biggest air-quality efforts, a rule that would curb emissions from coal-fired power plants in 28 states.

In a 90-minute argument session featuring analogies to last-second shots in tight basketball games, the justices questioned contentions made by challengers to the Environmental Protection Agency rule, which targets air pollution that crosses state lines.

The rule — struck down by a lower court and being challenged by power companies, states and miners — has never taken effect. It would force companies including Texas’ largest power producer, Energy Future Holdings Corp.’s Luminant, to shutter old plants or invest billions of dollars in pollution-control technology. The administration says the rule would prevent as many as 34,000 premature deaths a year.

The rule would use a modified cap-and-trade system to limit emissions of sulfur dioxide and nitrogen oxide in 28 states whose pollution blows into neighboring jurisdictions. All are in the eastern two-thirds of the country.

The court’s four Democratic appointees, at times joined by Chief Justice John Roberts and Justice Anthony Kennedy, suggested that the EPA had adhered to the language of the Clean Air Act. Had the EPA taken another approach, “it would have run contrary to the statute,” Roberts said.

Justice Samuel Alito isn’t taking part in the case, meaning the administration must persuade five of the other eight justices to revive the rule. A 4-4 split would leave intact the lower court ruling voiding the regulation.

The argument is one of two court clashes in Washington on Tuesday that will determine the future of Obama’s environmental agenda. Judges at a federal appeals court less than a mile away were considering a challenge to separate EPA standards on mercury and acid gases from power plants.

That same federal appeals court rejected the cross-state pollution rule last year. The court ordered the agency to continue to enforce a 2005 measure known as the Clean Air Interstate Rule until a viable replacement to the cross-state regulation can be issued — a process the Obama administration has said could take years.

Attorneys general from 14 states, led by Texas, are challenging the rule alongside Luminant, Entergy Corp., Edison International, Peabody Energy Corp., Southern Co. and the United Mine Workers of America.

The companies say the EPA improperly focused on the cost of emissions reductions, rather than basing its rule solely on the amount of pollutants created in each state.

That argument drew resistance from several justices, including Sonia Sotomayor, who said it would be “crazy” for the agency not to consider cost.

The EPA rule aims to implement what is known as the “good neighbor” provision of the Clean Air Act. That provision requires states to cut emissions that “contribute significantly” to pollution in another state.

A government lawyer, Malcolm Stewart, used the basketball analogy to argue that the EPA should be able to focus on the emissions that can be eliminated at the lowest cost. He said that a coach asked to explain a close loss would point to a missed easy shot, rather than a desperation shot at the final buzzer. Roberts later said he liked the analogy.

The states argue that the EPA didn’t give them a chance to put in place their own pollution-reduction plans before imposing a nationwide standard.

Roberts, who probed both sides, questioned the EPA’s approach, saying states were being asked to come up with plans before they knew how much pollution they had to eliminate.

“There’s no possible way for a state to know” how much EPA would require, he said.

Later, Roberts said that, while the states’ task “may be hard,” it was dictated by the Clean Air Act.

The states also say the EPA is requiring some upwind states to reduce pollutants that the agency has found are so minimal they don’t contribute to unhealthy air.