Senate legislation to curb unexpected high medical costs for patients moved ahead 20-3 without the support of presidential hopefuls Elizabeth Warren and Bernie Sanders, who voted against the measure by proxy because they were preparing for the Democratic debates in Miami.

The Senate Health, Education, Labor, and Pensions Committee advanced the Lower Health Care Costs Act Wednesday, putting it on track to hit President Trump's desk ahead of the August recess. The only other senator to vote against the bill was Sen. Rand Paul, R-Ky., who said he didn't think it would work.

The vote came after more than a year of bipartisan efforts from the HELP Committee. Polling from the Kaiser Family Foundation shows voters are most concerned about the affordability of medical care and prescription drugs. Affordability even ranks higher as a concern than extending care, which is a large part of the Democratic healthcare platform. Warren and Sanders support the Medicare for All Act, which would roll everyone living in the U.S. into a government plan.

The legislation , which contains 59 healthcare proposals, would help shield patients from “surprise medical bills” that come after patients receive medical care outside their network by setting a benchmark payment on what hospitals are allowed to charge and enacting other protections for patients. The bill also would make it easier for generics to get approved, which will make more less-expensive drugs available to patients.

It contains public health measures, such as authorization for an education campaign on vaccines at a time when measles rates continue to rise, and raises the minimum age to purchase cigarettes and vaping products from 18 to 21.

Warren said in a statement that she "cannot vote for a bill claiming to lower healthcare costs that does not take meaningful steps to halt the administration’s shameful sabotage of health coverage for millions of Americans or hold drug companies accountable for soaring prices that force families to decide between medications they need and paying rent or putting food on the table."

A representative from Sanders' office said he voted no due to his objection over the flat funding proposed over five years for Federally Qualified Health Centers and the National Health Service Corps, which they said would result in an absolute cut of nearly 20% to both programs.

"At a time when people are already struggling to afford their healthcare and access providers in their communities, this was a real missed opportunity to help the most vulnerable people in our country," Sanders' representative said. "Our office looks forward to working with our House counterparts to avoid this harsh cut.”

A debate emerged during the markup over whether the HELP Committee should have included a provision to allow a third-party arbiter to determine prices. That provision does not have the support of the White House, but it was part of a separate bipartisan bill called the STOP Surprise Medical Bills Act, led by Sens. Bill Cassidy, R-La., and Maggie Hassan, D-N.H.

The Cassidy-Hassan bill would have a similar benchmark plan as the legislation passed Wednesday but then if either the medical provider or the insurer wanted to appeal the amount, they could do so using an arbitration process.

Such a system would let an independent arbiter determine a fair price for a bill after evaluating what hospitals and doctors are charging compared with what insurers are willing to pay. The binding arbitration is supposed to give both sides an incentive to offer a realistic figure. It's often referred to as “baseball-style arbitration” because it's similar to how salaries are decided in Major League Baseball.

HELP Chairman Sen. Lamar Alexander, R-Tenn., said at the start of the hearing that the benchmark rating would be the most effective at lowering healthcare costs. But other senators who were in favor of adding the arbitration provision expressed their displeasure that it was not included.

“There was a delicate balance struck between insurance companies, hospitals and doctors,” Cassidy said of his legislation. “What has been adopted in entirely in the insurance companies’ interest.”

Sen. Mitt Romney, R-Utah, said he was concerned the benchmark-only approach would lead to shortages in healthcare providers.

"Having a potential for arbitration is an important one," he said.

The senators were in part assuaged after the committee added an amendment Cassidy, Hassan, and Lisa Murkowski, R-Alaska, introduced that would make it more clear to patients which providers are in their network.

The committee rejected an amendment from Sen. Chris Murphy, D-Conn., that would have the Department of Health and Human Services write a report within 30 days about what would happen if the lawsuit waged by GOP state officials seeking to undo Obamacare were to be successful. The report would need to be delivered by Congress within 30 days, and would include information about how many people could become uninsured as a result.

"We have to start expecting that this lawsuit will be successful," Murphy said. The lawsuit will be heard July 9.