President Donald Trump signed an executive order on Thursday to weaken the Obamacare law and make it easier for Americans to buy bare-bones health insurance plans, but the action faces possible legal challenges.
Stymied in Congress by the failure of Senate Republicans to pass legislation to dismantle Democratic former President Barack Obama’s signature domestic policy achievement, Trump’s order marks his administration’s latest effort to undermine the law without action by lawmakers.
Trump’s order was his most concrete step to undo Obamacare since he took office in January after promising voters he would dismantle the 2010 law.
“The cost of the Obamacare has been so outrageous, it is absolutely destroying everything in its wake,” he said at a signing ceremony in the White House.
Trump’s order gives people more access to plans that do not cover essential health benefits such as maternity and newborn care, prescription drugs, and mental health and addiction treatment. Obamacare requires most small business and individual health plans to cover those benefits.
Trump wants to make it easier for small businesses to band together as associations across state lines to buy cheaper, less regulated health plans with fewer benefits.
The order also seeks to change an Obama-era limit on the time span people can use short-term health insurance plans, which are cheaper but cover few medical benefits. Those plans are currently limited to three months.
Senate Democratic leader Chuck Schumer accused Trump of “using a wrecking ball to single-handedly rip apart our healthcare system.”
“Having failed to repeal the law in Congress, the president is sabotaging the system,” Schumer said in a statement.
Republicans, despite controlling the White House and both chambers of Congress, have failed since Trump took office to make good on their seven-year promise to repeal Obamacare, which they have called a government intrusion into Americans’ healthcare.
Trump said the order was “only the beginning” and that his administration would take additional actions. He said he would “pressure Congress very strongly to finish the repeal and the replace of Obamacare once and for all.”
Experts questioned whether Trump has the legal authority to expand association health plans.
The action could open Trump to legal challenges from Democratic state attorneys general, who have said they will sue Trump if he tries to destroy Obamacare, a law that brought health insurance coverage to 20 million Americans.
Experts said the association health plans could attract young, healthy people and leave a sicker, more expensive patient pool in the individual insurance markets created under Obamacare, driving up premiums.
Conservative groups and lawmakers have cheered Trump’s order. Republican Senator Rand Paul, who said he worked with Trump for months on the order, opposed the Senate’s most recent attempt to overhaul Obamacare because he said it left too many of Obamcare’s regulations and spending programs in place.
Shares of hospitals and insurers focused on the Medicaid health insurance program for low-income Americans have been particularly volatile this year due to efforts to roll back Obamacare.
Hospital stocks edged lower on Thursday morning, with HCA Healthcare down 1.4% and Tenet Healthcare down 2.3%. Medicaid insurers also fell with Centene off 2.6%.
Trump has taken a number of other steps since January to weaken or undermine Obamacare. He has not committed to making billions of dollars of payments to insurers guaranteed under Obamacare, prompting many to exit the individual market or hike premiums for 2018.
The administration also halved the open enrollment period, which begins Nov. 1, and slashed the Obamacare advertising and outreach budget.
This article originally appeared on FORTUNE