No more Clear Channel bids?

NEW YORK (CNNMoney.com) -- Shareholders may have muscled the private equity suitors pursuing Clear Channel into raising their offer for the radio station giant once, but don't expect it to happen again.

Scott Sperling, co-president of Thomas H. Lee Partners, says the buyout firms were reluctant to raise their bid the first time around, and insists they simply can't afford to increase it again.

"[Our financing sources] don't have anything left. We don't have anything left," he said at a private capital conference in New York on Tuesday.

Clear Channel (Charts, Fortune 500) agreed to be bought by private equity firms Thomas H. Lee Partners and Bain Capital in November of last year, but dissenting shareholders threaten to derail the deal.

In an effort to win over shareholders, the buyout firms raised their cash offer last week from $37.60 a share to $39 a share, or about $19.4 billion.

The Clear Channel deal highlights the growing tension between public shareholders and private equity firms. Shareholders have been highly critical of the deal, arguing it undervalues the company.

Sperling said he thought private equity firms were offering a fair price for Clear Channel, adding that the bidding was opened up to competitive auction.

He also noted the significant premium offered to shareholders. The bid on the table represents a premium of 33 percent over the average price the stock traded at in the 60 days before the company said it was exploring strategic options.

Now the fate of the deal is up to shareholders. A vote is scheduled for May 8 in San Antonio, where Clear Channel is based. The deal requires two-thirds approval of all shareholders.