President Trump on Thursday took executive action on health care, calling for a plan that could let employers band together and offer coverage across state lines as Congress stalls on efforts to overhaul ObamaCare.

“So this is promoting health care, choice and competition all across the United States,” Trump said as he signed the order in the Roosevelt Room of the White House. “This is going to be something that millions and millions of people will be signing up for and they're going to be very happy. This will be great health care.”

The president described the executive order as “the first steps to providing millions of Americans with ObamaCare relief.” He said he isn't giving up on getting lawmakers to repeal the law.

“We are going to also pressure Congress very strongly to finish the repeal and the replace of ObamaCare once and for all," Trump said.

The executive order aims to offer “alternatives” to ObamaCare plans and increase competition to bring down costs, the White House said.

The president was joined at the signing by several Republican lawmakers, including Kentucky Sen. Rand Paul, who called it “the biggest free market reform of health care in a generation.”

“This reform, if it works and goes as planned, will allow millions of people to get insurance across state lines at an inexpensive price,” Paul said.

TRUMP'S HEALTH CARE EXECUTIVE ORDER: WHAT TO KNOW

Trump said he will direct the secretary of labor to consider expanding access to Association Health Plans, which could allow employers to form groups across state lines offering coverage. The White House says these plans could offer lower rates.

“Insurance companies will be fighting to get every single person signed up," Trump said. "And you will hopefully be negotiating, negotiating, negotiating. And you'll get such low prices for such great care. Should have been done a long time ago and it could have been done a long time ago.”

Those "association health plans" could be shielded from some state and federal insurance requirements. But responding to concerns, the White House said participating employers could not exclude any workers from the plan, or charge more to those in poor health.

The order also calls on other federal agencies to consider expanding coverage in low-cost, short-term insurance plans not subject to ObamaCare rules.

It's unlikely to reverse the trend of insurers exiting state markets. About half of U.S. counties will have only one ObamaCare insurer next year, although it appears that no counties will be left without a carrier as was initially feared.

The move comes after congressional Republicans repeatedly have been unable to pass legislation repealing or reforming the Affordable Care Act, which critics say has led to rising premiums and diminishing coverage options – in some cases forcing consumers to lose their previous plans and doctors. Trump’s executive order could clear the way for cheaper, more bare-bones insurance policies.

Trump's order is likely to encounter opposition from medical associations, consumer groups and even insurers -- the same coalition that has blocked congressional Republicans. They say it would raise costs for the sick, while the lower-premium coverage for healthy people would come with significant gaps.

Cori Uccello, a senior health fellow for the American Academy of Actuaries, told Fox News that an issue with AHPs is regulation.

“There’s uncertainty of who is going to have oversight in terms of consumer protection. What redress does a consumer have, appeals processes, those kinds of things,” she said.

White House domestic policy director Andrew Bremberg told reporters during a conference call Thursday that the executive order is necessary because ObamaCare has caused “costs to skyrocket.”

Bremberg acknowledged Trump’s order could affect tens of millions of Americans and said the administration also intends to take “additional actions” on health care in the months to come.

The administration is hopeful these actions could be implemented within six months, a senior administration official said, but it could take longer to finalize.

Fox News' Kaitlyn Schallhorn and Serafin Gomez and The Associated Press contributed to this report.