U.S. President Donald Trump called on Congress on Thursday to pass legislation to protect patients from surprise medical bills from out-of-network doctors that can unnecessarily cost patients tens of thousands of dollars.

In remarks at the White House, Trump unveiled principles the administration will send to congressional lawmakers to incorporate into a legislative package that would address surprise bills.

“We’re going to hold insurance companies and hospitals totally accountable,” Trump said.

Surprise bills occur when patients visit a hospital they believe is in their health insurance network but then are seen by a doctor or specialist who is out of network.

The White House wants the legislation to particularly focus on patients who receive emergency room care and are unable to consent to out-of-network care.

The principles are also aimed at patients who visit a facility for elective surgery but are unknowingly treated and billed for treatment from a doctor or specialist who is not in their insurance network, Joe Grogan, head of White House domestic policy, told reporters.

America’s Health Insurance Plans, a trade group that represents U.S. health insurers, said on Thursday it supports prohibiting doctors from sending patients surprise bills in cases of emergency and requiring facilities to inform patients of their doctors’ insurance network status.

Congress has held hearings on the issue and a bipartisan group of senators is drafting a bill to protect patients from surprise bills. Democratic Senator Maggie Hassan, along with several Republican senators and representatives, attended the event.

The White House said it does not want federal expenditures to increase as a result of legislation. That could happen if Medicare, the government health insurance program for Americans aged 65 and older, and Medicaid, the government health insurance program for the poor and disabled, have to pay more of patients’ bills.

Democratic Representative Frank Pallone, chairman of the House Energy and Commerce Committee, and Republican Representative Greg Walden, the committee’s ranking member, said in a statement they would work on bipartisan surprise billing legislation.

“No family should be left in financial ruin through no fault of their own, which is why we have been working together on a bipartisan solution to protect patients that we hope to announce soon,” Pallone and Walden said.

Trump calls on Congress to protect patients from surprise medical bills