SCENARIOS-Britain's Brown survives, but for how long?

LONDON, June 9 (Reuters) - British Prime Minister Gordon Brown's new cabinet rallied round him on Tuesday, vowing to help in a daunting fight to win the next election after Brown snuffed out any immediate threat to his leadership.

Labour suffered its worst poll results in a national vote since 1910 this week, slumping to third place in European elections. A string of ministers has deserted Brown's government in the past week, many of them calling on him to stand down before the next election, which must be called by mid-June 2010.

Brown faced down dissent from some outspoken rebels at a tense meeting with some 350 Labour members of parliament on Monday night, winning over sceptics by admitting mistakes and taking responsibility for a week of political turmoil.

Foreign Secretary David Miliband, once seen as a potential challenger to Brown, said Labour was united behind Brown: "The Labour Party does not want a new leader, there is no vacancy, there is no challenger," he said. "So that is that."

So what happens next?

IS GORDON BROWN'S POSITION SAFE?

For now, yes.

The Labour rebels who spoke out against the prime minister have lost their best chance to oust him. If they cannot organise a revolt on the back of a string of high-profile cabinet resignations and disastrous local council and European elections, it is reasonable to assume they will not be able to stage a credible challenge for some time.

But further leadership speculation should not be ruled out -- especially in the run-up to the Labour Party's annual conference in September -- if poll ratings, which currently show Labour lagging up to 20 points behind the opposition Conservatives, remain poor.

After six cabinet ministers resigned in the past week -- several of them allies of former prime minister Tony Blair -- there are several big hitters among the ranks of Labour lawmakers who could attempt a more concerted move against Brown.

WHAT CAN BROWN DO TO SHORE UP HIS POSITION?

Brown needs to inspire his party with a more inclusive leadership and a clear direction that voters can buy in to after 12 years of Labour rule.

He has pledged to clean up parliament, which has been rocked by a scandal over outlandish, taxpayer-funded expenses claims by lawmakers.

He may also try some populist measures, such as announcing an inquiry into Britain's involvement in the unpopular Iraq war and postponing the part-privatisation of the Royal Mail postal service.

But his best chance of quelling dissent and beating the opposition Conservatives in an election rests on the economy.

Brown, finance minister for 10 years before taking over from Tony Blair as prime minister in 2007, has been central to global action to deal with the financial crisis.

A quicker than expected turnaround in Britain's recession-hit economy would justify Brown's fiscal stimulus and almost certainly boost his dismal opinion poll ratings.

SO WHAT HAPPENS NEXT?

Brown will probably stay as leader and wait until May 2010 to call an election -- he still has a significant majority in parliament -- but his waning authority may make it harder for him to push through any controversial or unpopular legislation.

In the meantime, Labour faces two by-elections for parliamentary seats in Glasgow and Norwich after the House of Commons speaker Michael Martin and member of parliament Ian Gibson were forced to step down in the row over politicians' expenses. Defeat in those would put further pressure on Brown.

WHAT DOES IT MEAN FOR THE INVESTOR?

The pound has taken a battering on the foreign exchanges because of political uncertainty. A shoring up of Brown's position could lend support -- and sterling was stronger on Tuesday.

Further efforts to unseat him would probably risk more weakness in the currency. In the longer term, UK assets such as government bonds are only likely to be affected if expectations of a clear victory by the Conservatives in the next election are seriously undermined.

The Conservatives were by far the most successful party in the European elections, but they did not make any significant gains and their share of the vote remained under 30 percent.

RELATIONS WITH EUROPE

The Conservatives have called for a referendum on the European Union's Lisbon reform treaty.

In the seemingly unlikely event of a general election this year, a Conservative victory would give the party a chance to try to hold the referendum before the treaty comes into force across the 27-nation bloc.

Ireland, which rejected the treaty in a referendum last year, remains key to ratification and will attempt to push it through via another public vote later this year.

The more likely scenario of an election in mid-2010 could therefore leave any Conservative government with the problem of how to respond to a post-Lisbon EU. They have said they would not let matters rest, but have not specified what they would do.

The success of the anti-EU UK Independence Party in the European elections, where they beat Labour, shows the depth of eurosceptic feeling in Britain. (Additional reporting by Kate Kelland and Sumeet Desai, editing by Mark Trevelyan) (For more stories on Brown's woes, click on [ID:nL31000088]