When the U.S. women’s soccer team and the U.S. Soccer Federation agreed recently to take the women’s pay-equity suit to mediation after the World Cup, it seemed like a sudden shift in a yearslong battle.

But from the day the players’ lawsuit against their employer was filed in March—just three months before their World Cup title defense began—team members made repeated personal appeals to U.S. Soccer Federation president Carlos Cordeiro attempting to resolve it, according to records viewed by The Wall Street Journal before the parties agreed to mediation.

The correspondence shows a tense back-and-forth between players and their employer under the pressure of a looming World Cup.

Top team members asked Cordeiro to meet with them to discuss the suit, in which all 28 members of the women’s national-team pool allege that U.S. Soccer illegally pays them less and provides them lesser playing, training and travel conditions than members of the U.S. men’s national team.

“Carlos—we are counting on your leadership and would very much like to speak with you in person,” one of the players wrote on April 1, when the team was in training camp preparing for two friendlies, including an April 7 match in Los Angeles. “We know you are committed to resolving these issues and would like your help getting past some issues with USSF’s lawyers.”