A former chairman of the BBC and ITV has accused channel bosses of breaching impartiality rules by threatening to stage election debates without David Cameron.
The Tory peer said the consortium of broadcasters had been self-important, incompetent and "shambolic" during negotiations over the events.
Writing in The Times, Lord Grade – who was at the BBC between 2004 and 2006 before becoming executive chairman of ITV – insisted: "Who do the broadcasters think they are?
"Their behaviour over the election debates leads me to believe they suddenly have grossly inflated and misguided ideas of their own importance."
The peer said that "for the first time in history" the broadcasters were "unequivocally playing politics" in seeking to force the hand of elected party leaders to agree to their terms.
He warned the television executives involved that they are not "guardians of democracy", arguing that the Prime Minister is free to refuse and "people are free to comment on the choice he makes".
The intervention comes as the issue of debates is set to be debated on the floor of the House of Commons. The Democratic Unionist Party (DUP) has triggered a discussion on the "badly managed" process to agree TV debates between party leaders ahead of May's poll.
DUP leader Nigel Dodds has insisted if the Scottish National Party (SNP) and Plaid Cymru continue to hold invites, his party should also be allowed to take part.
But speaking ahead of the debate, Dodds said he was "quite content" for the big nationwide parties to debate the issues alone.
He said: "It's difficult to think of a recent political event more badly managed by the people who wanted it most.
"Whether the TV election debates last time were a good or bad thing for the general election campaign, it's been the broadcasters who have most persistently campaigned for them.
"They've chopped and changed formats, blinked under pressure, refused to consult constructively and now are absurdly threatening not to have the Prime Minister present.
"My own party would have been and is quite content for the genuine, big parties to debate one another. But we've always said, if any UK regional parties are invited, we're invited too."
He added: "At the moment, due to the incompetence of the broadcasters, these debates are in chaos and may well not happen. In future, we need to follow the example of the US and have an independent commission arrange any such debates."
The DUP debate will follow a Prime Minister's Questions which could be dominated for a second week by talk of the debates between David Cameron and Ed Miliband.
The Tory and Labour frontbenches will also make contributions to the Opposition Day debate.
Responding to Lord Grade's comments, a Labour source said: "This shows how rattled David Cameron is over TV debates. It is a desperate move to send out a Tory peer to try to bully the broadcasters."