Spencer Platt/Getty Images Sen. Bernie Sanders (I-Vt.), a former Democratic presidential candidate, has vowed to hold President-elect Donald Trump accountable for his promises to help working people.

WASHINGTON ― Sen. Bernie Sanders (I-Vt.) warned Donald Trump that the president-elect would face stiff opposition if he tries to privatize the Department of Veterans Affairs. The remarks from Sanders, a former chairman of the Senate Veterans Affairs Committee, was a response to a report that Trump is considering the move.

“Privatizing the VA would be an insult to the more than 22 million veterans who risked their lives to defend our country and it would significantly lower the quality of health care they receive. Our goal, shared by The American Legion and other major veterans’ organizations, must be to improve the VA, not destroy it,” Sanders said in a statement Friday.

“We will vigorously oppose any and all efforts to privatize the VA,” Sanders added.

A Trump transition team official told The Wall Street Journal on Wednesday that full-scale privatization was “one of the options on the table,” as is a plan to allow veterans to opt out of the public system.

Trump is also considering candidates to lead the VA with ties to Concerned Veterans for American, a group funded by the billionaire Koch brothers that backs privatization, the The Washington Post reported earlier this month. CVA, unlike traditional veterans groups, such as the American Legion, arose four years ago and is primarily focused on politics rather than services.

The American Legion, the Iraq and Afghanistan Veterans of America, the Paralyzed Veterans of America and many other veterans organizations oppose privatizing the VA because they say that only a publicly run medical system, free from concerns about profit, has the versatility to serve the special needs of military veterans. They also worry that the vouchers the government would provide veterans to purchase private care under some proposals would fail to keep pace with the cost of services.

And creating a path for veterans to opt out of the VA system could ultimately sap it of funding, these advocates fear.

Few veterans advocates dispute that the VA continues to struggle with a major backlog that has resulted in veterans failing to receive critical health care. Amid rising anger about the wait times and reports that VA officials were deliberately covering them up, VA Secretary Eric Shinseki resigned in May 2014.

Sanders, then-chairman of the VA committee, negotiated a bipartisan VA reform bill in the summer of 2014 that increased VA funding and permitted veterans to seek private care under select circumstances. Republican colleagues, including Sen. John McCain (R-Ariz.), have praised Sanders’ efforts.

As a presidential candidate, Trump frequently touted the support he received from individual veterans and promised to improve the VA.

“There will be no more waiting in line,” Trump said in July.

But if Trump chooses to reform the VA through partial or total privatization, he may end up on a collision course with the American Legion and other mainstream groups popular among the veterans whose support he has trumpeted.

Privatization is a “slap in the face to what we stand for,” American Legion Executive Director Verna Jones said at a meeting with transition team officials earlier this month.