Players protesting the plan to play the 2015 Women's World Cup on artificial turf were denied a fast-tracked hearing in Canada over the dispute.
The Human Rights Tribunal of Ontario instead offered early mediation between the players and the Canadian Soccer Association. But the CSA announced late Friday it would not take part in mediation.
The tribunal's ruling and subsequent rejection by the CSA came the same day a group of U.S. senators wrote soccer's international governing body, FIFA, urging it to reconsider the decision to play on artificial turf.
FIFA and the CSA are overseeing the World Cup, which will be played in six Canadian cities next June and July.
The players, including Abby Wambach, claim that holding the World Cup on artificial turf amounts to gender discrimination because men play soccer's premier tournament on real grass.
The Human Rights Tribunal gave both sides seven days to accept mediation and the attorney for the players filed their acceptance on Friday afternoon.
The CSA indicated in a statement later in the day that it "is not willing to participate in an early mediation in this matter."
In her interim decision, tribunal vice chair Jo-Anne Pickel did not address the merits of the case but acknowledged that a resolution would have to come soon. Because of the "jurisdictional complexity" of the matter, she doubted that even an expedited hearing would result in a decision on time.
Hampton Dellinger, the attorney for the players, said he would now ask the tribunal to reconsider its decision not to fast-track the case.
"The tribunal's decision was based on a false assumption that CSA was willing to join the players at the negotiating table. Clearly, that is not the case; a hearing on the merits is now more important than ever," Dellinger said in a statement.
Earlier in the day, 13 U.S. senators joined in the players' protest. The women claim artificial turf makes them more prone to certain injuries, like turf burn, and impacts the way the game is played because the ball moves differently.
Led by Sen. Sherrod Brown of Ohio, the 12 Democrats and one Republican signed a letter urging FIFA to "reconsider this short-sighted and counterproductive decision."
"Currently ranked first in the world, the United States women's national soccer team has made our country proud time and time again," the senators said in the letter addressed to FIFA President Sepp Blatter. "As members of the United States Senate, we are deeply concerned with FIFA's treatment of these players. We urge you to begin good faith negotiations with these athletes, free of retaliation and with the equal treatment that they deserve."
The letter comes in the wake of claims that some players are being pressured to remain silent on the issue or remove their names from the legal action. The CSA has denied the allegations.
The human rights complaint, which names both FIFA and the CSA, was filed with the tribunal on Oct. 1 by a group of players, including Americans Wambach and Alex Morgan, Germany's Nadine Angerer, Japan's Yuki Ogimi, and Spain's Veronica Boquete.
The senators penned a separate letter to U.S. Soccer's Sunil Gulati urging him, in his role as federation president and member of the FIFA executive committee, to join the players in their effort to put the tournament on natural grass.
Officials from FIFA and the CSA have said there are no plans to change the playing surface.