WASHINGTON -- The Trump administration's latest move against "Obamacare" could jeopardize legal protections on pre-existing medical conditions for millions of people with employer coverage, particularly workers in small businesses, say law and insurance experts.

At issue is Attorney General Jeff Sessions' recent decision that the Justice Department will no longer defend key parts of the Obama-era Affordable Care Act in court. That includes the law's unpopular requirement to carry health insurance, but also widely supported provisions that protect people with pre-existing medical conditions and limit what insurers can charge older, sicker customers.

Two independent experts said Wednesday that the administration appears to be taking aim at provisions of the ACA that protect people in employer plans, not only the smaller pool of consumers who buy a policy directly from an insurer. The new Trump administration position was outlined last week in a legal brief filed by the Justice Department in a Texas case challenging the Obama health law.

Workers "could face the prospect of insurance that doesn't cover their pre-existing conditions when they enroll in a plan with a new employer," said Larry Levitt of the nonpartisan Kaiser Family Foundation.

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University of Michigan law professor Nicholas Bagley said the administration does not appear to have thought through all the consequences of moving against one provision of a health law that has many complicated interlocking parts.

"The lack of care on the brief is jaw-dropping," said Bagley, who supports the Obama health law but considers himself a "free agent" critic of both sides. "There is no question that the Trump administration has to clarify what the scope of its injunction would be and grapple with the consequences of mowing down parts of the ACA.

"For someone with a pre-existing condition thinking about switching jobs, the answer to the question could make a life-changing difference," added Bagley.

Both Bagley and Levitt said their questions about the administration's intentions arose from language in the Justice Department brief that specifically singles out sections of the health law that apply to employer plans. The ACA strengthened previous protections already in federal law that limited the circumstances and length of time under which an employer could exclude coverage for a worker's pre-existing health problems.

The Trump administration had no immediate rebuttal to the issues raised by the two experts.

Instead, the Health and Human Services Department pointed to comments earlier in the week by Secretary Alex Azar, who told senators that the Justice Department brief was a legal and constitutional argument, not a policy statement.

"We share the view of working to ensure that individuals with pre-existing conditions can have access to affordable health insurance," Azar said. "The president has always shared that and we look forward to working with Congress under all circumstances towards achieving that."

Nearly 160 million workers and family members have coverage through employers, although the number covered by small employers is much smaller.

A health policy expert with a business organization that represents large employers said he doubted there would be much of an impact on major companies, which are better able to pool risk and have long been accustomed to covering all employees regardless of health issues.

"There will not be a change with anyone who is with a very large employer," said James Gelfand of the ERISA Industry Committee, as the group is known. ERISA is the name of a federal law that governs employee benefits for big companies.

However, Gelfand said the impact could "spill over" to small businesses.

Separately, senior Republicans in Congress are wasting no time in trying to distance themselves from any effort by the administration to undermine popular protections for their constituents. Democrats are accusing Republicans of yet another effort to "sabotage" coverage, and plan to take the issue into the fall midterm elections.

"No American should be denied health coverage based on their pre-existing medical conditions," Sen. Orrin Hatch, R-Utah, said Wednesday. Hatch chairs the Finance Committee, which oversees health care and tax law. He supported repeal of the ACA's insurance mandate, but draws a line on pre-existing conditions.

"Everybody I know in the Senate - everybody - is in favor of maintaining coverage for pre-existing conditions," said Majority Leader Mitch McConnell, R-Ky, earlier in the week. "There's no difference of opinion about that whatsoever."

Added Sen. Lamar Alexander, R-Tenn., "There's no way Congress is going to repeal protections for people with pre-existing conditions who want to buy health insurance. The Justice Department argument in the Texas case is as far-fetched as any I've ever heard."

The lawsuit, filed in February by Texas and other GOP-led states, is in many ways a replay of the politically divided litigation that ended with the Supreme Court upholding the health care overhaul in 2012. In this case, California is leading a group of Democrat-led states in defending the law.

The Trump administration's stance is a rare departure from the Justice Department's practice of defending federal laws in court.