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LONDON, England (CNN) -- The acrimonious row over the timing of the departure from office of British Prime Minister Tony Blair has grown with the resignation of a dissident minister and six ministerial aides.
Junior defense minister Tom Watson said he quit Wednesday because it was "no longer in the interest of either the party or the country for Tony Blair to remain in office."
Six lawmakers acting as unpaid aides to government ministers also resigned within hours of each later in the day rather than remove their names from a letter demanding Blair set a timeframe for his departure.
Blair later rounded furiously on Watson, branding him "disloyal, discourteous and wrong" for signing an open letter calling for the prime minister to step down.
Speculation about Blair's future has grown since October 2004 when he announced he would not serve a fourth term as prime minister, later promising to hand over to a successor before a likely 2009 national election.
More recently, critics within the ruling Labour Party have openly started to voice concerns that the uncertainty over when Blair steps down is damaging its electoral hopes, while Blair's waning popularity is helping the resurgent opposition Conservative Party under new leader David Cameron.
CNN's European Political Editor Robin Oakley said Blair returned from his holidays this summer trying to divert attention from the leadership row by saying the party should stop being obsessed by the date of his departure. "That basically failed," said Oakley.
Then loyalists such as former parliamentary party whip Hilary Armstrong said Blair would likely be gone by next year's party conference, usually held in October. "That hasn't worked either," said Oakley.
"Now there is what many people are taking to be an authorized leak to the Sun tabloid -- the largest circulation British daily paper and one that has been given scoops before -- saying that Tony Blair intends to go on May 31.
"After an 8-week leadership campaign or so, he would then hand over as leader on July 26.
"Downing Street says it's not going to give a running commentary on dates but they are also not categorically denying that story. So it's going to become the perceived wisdom about when Blair is going to go, I think."
The Sun cited no sources for its report. The paper, owned by Rupert Murdoch's News Corporation, has backed Blair since he took office in 1997.
Oakley said Blair already felt badly weakened by his announcement that he would not serve a fourth term. "Now he feels that if he names a precise date all his remaining authority will drain away from him as everyone maneuvers to please his likely successor, Chancellor of the Exchequer (finance minister) Gordon Brown.
"Brown would become a much stronger figure while Blair would become a yet weaker figure."
Blair was appointed Labour leader in July 1994 and took office on May 2, 1997. He led his party to its third straight win at the polls last year -- a record for Labour -- but voters sharply reduced its majority in parliament.
Downing Street declined to comment or deny The Sun's story.