The row over election night counting threatened to worsen last night, as Returning Officers revolted over Government plans to force them to hold counts on election night itself, rather than the next day.

I can reveal that more than 100 Returning Officers have signed a letter to the Electoral Commission threatening to withhold their services if they are forced to count overnight. They don't use the word, but essentially they are threatening to go on strike! If they carry through on their threats ballot boxes could remain unopened for days if not weeks, and the result of the general election might remain in doubt for some time.

It has emerged that under an obscure piece of legislation passed by Parliament in April 1921, it is impossible to remove a Returning Officer once he or she has been appointed. Only in the event of their death can they be replaced. This means that once the election is called and their appointment is confirmed they have to remain in office and no one else - including the Electoral Commission or the Ministry of Justice - has jurisdiction over the conduct of the poll on the day or the count itself.

Ministers are said to be considering emergency legislation which could be introduced into the Commons next Tuesday and forced through Parliament before it is prorogued on Thursday. This legislation would enable the Electoral Commission to take over the functions of any Returning Officer, who, for whatever reason, was failing to carry out his duties.

I tried to get a comment from the Electoral Commission but they were remaining tight-lipped, as was Jack Straw's special adviser, Mark Davies.

There is even a suggestion that the dispute might even prevent the Prime Minister from announcing the election, as expected on Tuesday. Sources close to Number 10 are saying that the Prime Minister has ordered Jack Straw to get the situation sorted by the weekend but if he is unsuccessful, Downing Street strategists are now looking at having to hold the election on 13th or 20th May. A complicating factor is that the local elections, by law, must take place on 6th May. Parliamentary draughtsmen are looking at whether a clause could be inserted into any emergency legislation to enable the local elections to be delayed until any Thursday between 13 May and 3 June, the last possible date for a General Election.

I will try to get further details during the course of the day.