(Reuters) - Democratic presidential candidate Bernie Sanders, who bills himself as a champion of organized labor, found himself in an escalating feud with Nevada’s Culinary Workers Union on Wednesday, 10 days before the state holds the party’s third nominating contest.

FILE PHOTO: Democratic U.S. presidential candidate Senator Bernie Sanders addresses supporters at his New Hampshire primary night rally in Manchester, N.H., U.S., February 11, 2020. REUTERS/Mike Segar

Tensions have been simmering for months between the powerful 60,000-member union and the 77-year-old U.S. senator, who comes to Nevada after a strong showing in Iowa and victory in New Hampshire on Tuesday.

The union, which criticized Sanders’ universal healthcare plan in a flyer to its members on Tuesday, said on Wednesday his supporters responded by “viciously” attacking the organization via Twitter, text, voicemails and direct messaging.

The Nevada union, with outsized influence in a state heavily dependent on tourism, is against Sanders’ Medicare for All plan, a government takeover of healthcare that would end private healthcare insurance.

“It’s disappointing that Senator Sanders’ supporters have viciously attacked the Culinary Union and working families in Nevada simply because our union has provided facts on what certain healthcare proposals might do,” Geoconda Argüello-Kline, the union’s Secretary-Treasurer, said in a statement, without sharing specific attacks.

Sanders’ campaign responded with a statement defending his plan as guaranteeing comprehensive care.

“The program is crafted with the working class and particularly union members in mind,” Sarah Michelsen, Bernie 2020 Nevada State Director, said in a statement.

U.S. labor unions have spent years negotiating high quality, union-backed health care plans they fear will be snatched from them if a single-payer, government-run healthcare plan becomes reality.

Sanders’ rivals jumped into the fray on the issue on Wednesday, with the former mayor of South Bend, Indiana, Pete Buttigieg, touting his Medicare for All Who Want It, which does not preclude private insurance.

Former Vice President Joe Biden, the one-time front-runner who finished a disappointing fourth in Iowa and fifth in New Hampshire, referred to the union’s statement in a tweet and said, “supporting labor means supporting our unions.”

The Nevada Culinary Workers Union has yet to endorse any Democratic presidential candidate.