The fight over a $19 billion buyout of radio chain Clear Channel Communications may have just started—but it has already drawn blood.

Clear Channel says it has won a temporary restraining order from a Texas judge against the banks that had agreed to finance the deal, requiring them not to interfere with the buyout by refusing to fund it or demanding new terms.

Six banks—Citigroup, Morgan Stanley, Credit Suisse, the Royal Bank of Scotland, Deutsche Bank, and Wachovia—had made commitments for more than $22 billion of financing for the buyout by Bain Capital and Thomas H. Lee Partners. But the market for deal debt has eroded.

The company said that Judge John Gabriel of the state district court in Bexar County, Texas, found on Wednesday night in favor of its claim that "irreparable harm would result if the banks were not immediately enjoined from tortiously interfering with the merger agreement."

The banks have not yet responded to the judge's order.

On Wednesday, both Clear Channel and the two buyout firms sued the banks in New York and Texas courts.

"The financial risk to the banks in this suit dwarfs any risk they think they have in funding the debt," said Mark Mays, chief executive of Clear Channel Communications. "The behavior of these banks is irresponsible, unprofessional, and unjustified."

The firms say that the banks have tried to renege on the commitments they made nearly a year ago. "It seems clear that lenders' remorse set in when credit markets worsened," the firms said in a statement. "Now they are trying to walk away from their commitment letter which clearly states that they bear all the risk that conditions in the debt markets might change."

The deal, first announced in November 2006, is now for $39.20 per share. On Wednesday, Clear Channel shares tumbled 17 percent, to $26.92, amid reports that the buyout was collapsing.

The question is whether the legal squaring off is all for show—a prelude to a renegotiated buyout at a lower price.

Steven Davidoff, the deal professor on DealBook, points out that the plaintiffs in the Texas lawsuit have brought in a big gun: Joe Jamail, the lawyer who in 1985 won a $10.5 billion verdict against Texaco for interfering with a deal between Pennzoil and Getty.