DAVID Cameron has said he has "a lot of sympathy" with the DUP's protests at being excluded from the proposed general election TV debates.
The British prime minister said there was a difficulty with the broadcasters' plans which include the Scottish National Party and Wales's Plaid Cymru but not the DUP.
Mr Cameron's comments will add to speculation that the TV debates will not go ahead due to disagreement between proposed participants and broadcasters over the format and which parties are included.
He spoke after the DUP's Nigel Dodds slammed the broadcasters' plans as "unfair, irrational and legally implausible".
The BBC Trust is considering an appeal from the DUP - the fourth largest party in the Commons with eight seats - against its exclusion from the debates.
During Prime Minister's questions in the Commons, Mr Dodds said: "As we have heard, the prime minister and the leader of the opposition agree that the reputation of politics needs improving.
"But would you agree that the latest format put forward by the broadcasters for TV election debates won't contribute to that?
"The broadcasters need to realise that these debates are for the benefit of voters as well as themselves and that the unfair, irrational and legally implausible exclusion of the people of Northern Ireland from those debates and particularly the DUP which has more votes and more seats than some that are included, cannot be justified.
"So will you agree with us to go back to the broadcasters, demand a rethink, on the basis of justice and fairness and that they come forward with the proposals that you and the rest of us can agree to?"
Mr Cameron replied: "I have a lot of sympathy with what you say.
"My argument was that you couldn't include one minor party without another minor party and obviously I was referring specifically to the Greens on that occasion.
"But now having decided to include Plaid Cymru and the SNP there does seem to be a difficulty in not addressing the question of the DUP.
"But I'm sure your case should be taken seriously."
If the debates proceed as planned, Mr Cameron and Labour leader Ed Miliband will be pitched in a head-to-head showdown on Sky and Channel 4 exactly a week before the May 7 general election.
ITV won the right to stage the first debate, scheduled for April 2, which will put Mr Cameron and Mr Miliband against Liberal Democrat Nick Clegg, Ukip's Nigel Farage, the Greens' Natalie Bennett, the Scottish National Party's Nicola Sturgeon and Leanne Wood of Plaid Cymru.
The same line-up of seven leaders has been invited to take part in the second debate, a fortnight later on April 16, which will be hosted by the BBC.
And the final showdown between the two men most likely to emerge from the general election as prime minister has been scheduled for April 30 on Sky News and Channel 4.