The organization chosen to taken over Long Island College Hospital is asking the courts to issue an injunction.
Brooklyn Health Partners says SUNY Downstate engaged in unfair negotiations.
Its complaint comes after questions were raised about the group's ability to take control of LICH and maintain a full-service hospital.
Those concerns led Mayor Bill de Blasio to ask SUNY to reopen negotiations with other bidders.
Merrell Schexnydre, the president of BHP, says they just want to follow through on the deal that's already been agreed upon.
"At this point, going in front of the judge to see if we can get an injunctive relief so that we can get our project closed, put down the $25 million and begin to build a full-service, state-of-the-art hospital," Schexnydre said.
Crain's reported Thursday that a private equity firm called Trindade Value Partners has raised its offer for LICH by $90 million
It said the extra money would cover operational and pension costs for up to one year.
Trindade is promising to build a new 506-bed hospital at the LICH site.
SUNY Downstate is set to give up control of LICH on May 22.