Talks over the $20 billion leveraged buyout of U.S. radio operator Clear Channel Communications Inc. are in trouble, with the banks financing the deal unwilling to take a mark-to-market loss, a source familiar with the situation said on Tuesday.

But the final resolution is unclear, with the buyers still wanting to do a deal, the source said.

Clear Channel last year struck a deal to be bought by private equity firms Thomas H. Lee Partners and Bain Capital Partners LLC for $39.20 a share. The stock has traded significantly lower than that in recent months on fears the deal could also be in jeopardy.