Are the credits already rolling for Britain's embattled Gordon Brown?

With members of his own party calling for him to step down, Labour's leader faces a key test with today's elections. Is Alan Johnson, a former postman, poised to become the next prime minister?

LONDON – As political rebellions go, this one's already got a snappy title: 'The Hotmail Coup."

A plot to unseat Britain's beleaguered Prime Minster Gordon Brown is reaching a climax among senior members of Britain's ruling party, who are thought to be using the popular e-mail service to lay the groundwork for a heave that could take place against their leader as early as next week.

After months of negative headlines on everything from the economy and his supposed lack of charisma , to a recent scandal about excessive expenses claims by parliamentarians (click here for a story on the woes facing Parliament), Mr. Brown is fighting for his political life amid a meltdown in his government, which has seen no less than four of his ministers quit their jobs this week.

The political bloodletting was put on hold today as Britons went to the polls to vote in elections for local councils and the European Parliament (more Monitor coverage of the elections here), the results of which will be the deciding factor in whether Brown is forced out of the prime ministerial offices at London's 10 Downing Street.

Dubbed the "Gordinator" by some for his apparent ability to continue in the job despite taking hit after hit, Brown's chances of hanging on are likely to evaporate as his party heads for what many believe will be its worst electoral drubbing in its history.

When the European results are released on Monday, the party might even finish in fourth place, the victim of voter anger that is likely to see many Labour voters today desert to the opposition, plump for smaller protest parties, or just stay at home, analysts say.

With political observers likening the recent departures of once-loyal Labour ministers to rats leaving a sinking ship, the latest to step down was Communities Minister Hazel Blears, who quit on Wednesday after facing intense criticism over her allowances claims.

Her resignation letter once again alluded to claims by her that the prime minister had lost touch with ordinary voters, while television pictures of the MP returning home to the north of England showed her wearing a broach inscribed with the words "Rocking the Boat."

Attention is now turning to a letter, details of which have already been leaked to the media, which plotters against Brown are preparing to deliver to him (more British media coverage here).

The Guardian newspaper is reporting that the so-called Labour rebels hope that a new leader could be installed as early as July 2. "Dear Gordon," begins their letter, "Over the last 12 years in government, and before, you have made an enormous contribution to this country and to the Labour Party, and this is widely acknowledged.

"However we are writing now because we believe that in the current political situation, you can best serve the Labour Party and the country by stepping down as party leader and prime minister."

Mark Wickham-Jones, a professor of politics at Bristol University and an expert on the Labour Party, put Brown's chances of surviving the next few days at 50/50.

"He needs to at least manage to stabilize the situation," Professor Wickham-Jones says, naming his most likely successor as the health secretary, Alan Johnson, a smooth-talking Londoner whose backstory as a former postman may help Labour reconnect with its grassroots.

Don't expect any major policy shifts from Britain in the event of a change at the top, though.

Wickham-Jones adds, "The reality is that the economic situation determines what anyone in government can do. Johnson is a middle-of-the-road, pragmatic individual, but all policy is and will be shaped by the banking crisis."