Ginger Media Group, which bought Virgin Radio last year, pulled out after clashing with other investors over the structure of the consortium, called Digital One, at a meeting on Wednesday night.
Apax, the venture capital group which supported Ginger, is also believed to have refused to commit itself to the investment. "Ginger basically hasn't got any money," one source said last night.
At the same time, cable and transmissions group NTL said it was joining the consortium.
GWR, which owns Classic FM, will lead the bid with a 51 per cent shareholding. Talk Radio will also be taking part.
National digital radio is due to be launched next year. It will carry the three national commercial radio stations - Classic, Virgin and Talk - but will be able to broadcast a host of other channels. It will also support high-speed data transmission.
David Campbell, Ginger's chief executive, said Virgin would still broadcast on the digital multiplex. "We remain supportive of the digital radio consortium and wish Digital One every success," he said.
Meanwhile, London News Radio and a management buyout team are today expected to submit a bid for Talk Radio. Kelvin MacKenzie, the former Sun editor, is also attempting to buy the station.