Martin Heinrich was one of 13 Democratic U.S. senators who voted against legislation earlier this week that would have allowed Americans to buy prescription drugs from other countries.

The measure, a health care reform idea often supported by progressives, came as an amendment to legislation aimed at changing Senate rules to allow majority votes on budget bills. The procedural changes, which the Senate narrowly approved in the early hours of Thursday, are the first step in Republican plans to repeal as much of the Affordable Care Act, known as Obamacare, as they can.

Bernie Sanders, the Vermont independent senator who unsuccessfully ran for the Democratic Party presidential nomination last year, sponsored the amendment with Sen. Amy Klobuchar, D-Minnesota. Senators rejected the amendment on a 52-48 margin, with 12 Republicans casting their votes in favor.

After the amendment went down Wednesday night, many critics took to social media to blast Heinrich and the 12 other Democrats who voted against the amendment.

In a prepared statement, Heinrich cited the amendment’s lack of Federal Drug Administration safety protocols for the prescription drugs from other countries as his reason for voting against it. He also signalled support for letting the federal government negotiate lower prices with businesses.

“I have been fighting for years to allow the federal government to use its negotiating power to secure cheaper prescription drugs,” Heinrich said, “and I support importation if we can ensure FDA safety standards to protect consumers.”

Sen. Corey Booker, D-New Jersey, gave similar reasons for his “no” vote on the amendment. Allowing prescription drugs from other countries to be sold without FDA safety protocols could open the way for fly-by-night drug companies to sell unsafe, wrongly labeled drugs, he argued.

“Any plan to allow the importation of prescription medications should also include consumer protections that ensure foreign drugs meet American safety standards.” Booker’s spokesperson told Jezebel. “I opposed an amendment put forward last night that didn’t meet this test.”

Heinrich spokeswoman Whitney Potter also pointed to Heinrich’s support of another failed amendment Wednesday night that would have required Congress to come up with plans to lower prescription drug prices.

Heinrich’s statement also emphasized his support of the ACA.

“If we let the Republicans repeal the Affordable Care Act, seniors will face an additional $1,000 per year in out of pocket costs for these same drugs,” he said.

For years, many progressives have supported the idea of allowing the sale of prescription drugs from other countries, particularly Canada, as a means to lower prescription drug prices in the U.S., where the pharmaceutical industry has tremendous influence.

Canada, for example, has price controls in place for its prescription drugs. The U.S., on the other hand, prevents the federal government from negotiating with drug companies to lower prescription prices for any health care plans under Medicare Part D. When the Medicare expansion law passed Congress in 2003, critics cited this exemption as a giveaway to the pharmaceutical industry.