House Republicans point to the support they received from constitutional scholars who testified on the ACA mandate delay last December.
At a House Judiciary Committee hearing, George Washington University law professor Jonathan Turley, a once fierce critic of the Bush administration, suggested Obama overreached.
"The president is required to faithfully execute the laws. He's not required to enforce all laws equally or commit the same resources to them," he said. "But I believe the president has crossed the constitutional line."
Administration officials have repeatedly argued that alterations to the ACA are legal.
In February 2013, a Treasury Department spokeswoman told Government Executive the administration has the power to delay the employer mandate and its fines, which are in essence taxes on businesses that do not comply with the law.
The taxing authority of the federal government was the legal underpinning of the Supreme Court's decision to uphold the sweeping health law and its individual mandate in 2012.
But other legal experts have already said any lawsuit around executive authority would face challenges.
In order for it to be formally considered by the courts, House Republicans must prove that the chamber was somehow injured as an institution.