WASHINGTON (AP) — President Donald Trump will begin a push Thursday to fight health care sticker shock by limiting "surprise medical bills," the unexpected charges faced by insured patients when a member of a health care team that treated them is considered an out-of-network provider.

Senior administration officials told The Associated Press the Republican president will outline principles he can support as part of legislation to limit such billing practices. Republican and Democratic lawmakers have been trying to make progress on the topic for months, and White House support could improve chances that something gets done.

Patients being treated for medical emergencies often are in no position to check into whether their insurers have contracted with their surgeons or anesthesiologists to provide medical care. Trump wants to make it clear that patients who receive emergency care should not be hit with charges that exceed the amount paid to in-network providers.

The officials said the legislation also should protect patients seeking elective care by ensuring that they are fully informed before scheduling their care about which providers will be considered out of network and what extra costs that will generate.

The officials spoke on the condition of anonymity because they were not authorized to speak publicly on the matter before Trump's announcement. The White House effort is part of a broader push by the Trump administration to increase transparency in the health care system. On Wednesday, the administration finalized regulations requiring drug companies to disclose list prices of medications costing more than $35 for a month's supply.

The president also will make the case that legislation should not lead to additional costs for taxpayers.

Insurers form networks of doctors and hospitals, in part, to gain some leverage for negotiating reimbursements. Usually patients pay a bigger share of the bill for any care sought outside those networks.

But sometimes, patients don't know they got care outside of their network until they get their bill.

A House panel held a hearing on surprise medical bills last month. Trump also participated in a January meeting with health care advocates and victims of surprise billing. The officials said Trump made clear following the meeting that he wanted his administration to work on finding a fix.

States also have been working to protect consumers from surprise medical bills. A survey of states by Georgetown University found that about half the states have acted to protect consumers, but some, such as California, Connecticut, Florida and a handful of others, have the most comprehensive protections.

Jack Hoadley, a research professor emeritus at Georgetown, told lawmakers last month that unexpected medical bills are a major concern for consumers, with two-thirds of Americans saying they are "very worried" or "somewhat worried" that they or someone in their family will receive a surprise bill.

He said programs like Medicare, Medicaid and veterans care protect consumers from out-of-network bills. But the same protections do not exist for most private insurance.