President Obama’s federal health care law may be headed to the Supreme Court – again.

The high court has been asked to review a July 22 ruling by the Fourth Circuit Court of Appeals that declared constitutional all federal subsidies granted to enrollees of the health care system.

The losing plaintiff in the case officially appealed the ruling in a petition Thursday to the Supreme Court.

The Fourth Circuit ruling contradicted another announced hours earlier by a three-judge panel of the U.S. Court of Appeals for the District of Columbia that ruled the IRS went too far in extending subsidies to those who buy insurance through the federally-run exchange, known as HealthCare.gov.

It is likely to take weeks, if not months, to learn if the Justices will even take up the petition. It also is not yet clear how -- or if -- the Obama administration will appeal the first ruling.

The July 22 rulings involve two of four cases challenging the subsidies afforded under the health care law and their outcomes are being closely watched by both sides.

Some 90 percent of the total number of federal exchange enrollees are eligible for subsidies because of low or moderate incomes. How they pay for their insurance could be greatly affected if the Supreme Court were to rule those subsidies are unconstitutional.

An estimated $1 trillion in total subsidies is expected to be spent over the next year if the program is left untouched.

The Affordable Care Act already has survived one Supreme Court challenge in 2012, when the Court ruled 5-4 that the federal government could require Americans to purchase insurance or pay a penalty.

It recently lost another challenge in a case brought by Hobby Lobby. In that 5-4 ruling, the Court said the closely-held for-profit corporation could opt out of providing contraceptives through its employee health insurance based on religious beliefs.