WASHINGTON -- Pressure is mounting on USA Hockey in its wage dispute with the women's national team.

On Monday, 16 U.S. senators wrote a letter to executive director Dave Ogrean, urging him to resolve the matter. The message came four days before the start of the women's world championship, which players threatened to boycott if significant progress was not made toward an agreement.

USA Hockey's board of directors held a meeting Monday afternoon, but had not emerged with a resolution as of late Monday night. Players said Sunday in a statement that they were hopeful USA Hockey would agree to what was hammered out after 10-plus hours of in-person talks a week ago.

The senators, all Democrats, cited the Ted Stevens Olympic and Amateur Sports Act and told Ogrean he should ensure the team receives "equitable resources."

They joined a chorus of support that includes unions representing players from the NHL, NBA, NFL and Major League Baseball. Those organizations said over the weekend they stood with the women's team and criticized USA Hockey for attempting to find replacement players.

Prominent NHL agent Allan Walsh tweeted Sunday, "Word circulating among NHL players that American players will refuse to play in men's World Championships in solidarity with the women."

Zach Bogosian, an American-born Buffalo Sabres defenceman, went to high school with U.S. captain Meghan Duggan. He tweeted his support and said he hopes the dispute is resolved.

The U.S. is the defending champion at the International Ice Hockey Women's World Championship, which begins Friday in Plymouth, Michigan.

In negotiations over the past 15 months, players have asked for a four-year contract that pays them outside the six-month Olympic period. The senators' letter notes the $6,000 that players earn around the Olympics and USA Hockey's $3.5 million annual spending on the men's national team development program and other discrepancies.

"These elite athletes indeed deserve fairness and respect, and we hope you will be a leader on this issue as women continue to push for equality in athletics," the senators wrote.

The letter was signed by: Elizabeth Warren and Edward Markey of Massachusetts, Patty Murray of Washington, Dianne Feinstein of California, Patrick Leahy of Vermont, Richard Blumenthal of Connecticut, Maggie Hassan of New Hampshire, Sherrod Brown of Ohio, Thomas Carper of Delaware, Tammy Baldwin of Wisconsin, Robert Menendez and Cory Booker of New Jersey, Mazie Hirono of Hawaii, Bob Casey of Pennsylvania, Kirsten Gillibrand of New York and Amy Klobuchar of Minnesota.

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AP Hockey Writer John Wawrow contributed to this report.