Blair's triple challenge

By BBC News Online political correspondent Nick Assinder

Tony Blair is facing his greatest election test since Labour's "black summer", with three by-elections next Thursday.

The polls in Preston, West Bromwich West and Glasgow will give thousands of voters a chance to deliver their verdict on how the government is currently performing.

And they come just six months before the expected general election, when Labour is praying for an historic second term.

Voters will have their say on the government

The results will not only give a detailed snapshot of how the parties are lining up, but could even help decide the timing of the next election.

All three are traditionally rock-solid Labour seats but, with Labour's giant opinion poll ratings now a thing of the past, party workers know they can afford to take nothing for granted.

The biggest fear will be Labour voters refusing to come out and support the government.

It is a trend that was witnessed in previous polls and has the potential to seriously erode the party's support.

A single loss for Labour would be disastrous, but large falls in its majorities - between 15,000 and 18,500 - would also be a major setback for Mr Blair.

The parties are pulling out all the stops for the polls with the SNP in Scotland and the Liberal Democrats and the Tories in England looking for real advances.

On the slide

Mr Blair is hoping that he has finally put the worst of the last year behind him and that voters will come out and support his candidates.

Earlier in the summer there were signs of widespread disillusion with the government.

Traditional Labour supporters were said to be disappointed that their government had failed to deliver on key election pledges.

And Tory leader William Hague started to make significant advances on issues like law and order and pensions.

For the first time since his landslide 1997 election victory, the prime minister saw the government's opinion poll ratings crashing and even his personal popularity on the slide.

Then there were major upsets, including the fuel tax protest and the pensions rebellion which came to a head at the party conference.

But thanks in part to a powerful end-of-conference speech this autumn, Mr Blair managed to turn the tide.

The opinion polls have been coming back to him, albeit at a more realistic level than previous showings.

He will be looking to the by-elections to show that the trend is still in his favour.

William Hague, on the other hand, wants to see more concrete signs that he has put the Tories back on track for the election.

A year ago any talk of a Tory victory at that poll was laughed out of court. Then, after his highly-successful summer, things took a turn for the better.

At the party conference last month activists were talking about a general election victory with a straight face.

Personal vote

That still looks highly unlikely, but Mr Hague will want to see clear indications that he is still chipping away at Labour's lead.

Liberal Democrat leader Charles Kennedy will also be searching the results for signs that he can increase his party's showing at the next election.

His candidate, Sandra Gidley, pulled off a sensation earlier in the year by snatching the safe Tory seat of Romsey, where the Labour vote collapsed.

Mr Kennedy has done his best to distance himself from the government, fearing voters may see his party as nothing more than an optional add-on to Labour.

In Scotland, the SNP will mount a powerful challenge in Anniesland but few expect them to match the sensational result in Hamilton earlier in the year when they reduced the Labour majority from 16,000 to 556.

One of the problems for Labour is that in all three seats there was a strong personal vote for the sitting MPs.

Former Scottish First Minister Donald Dewar was a hugely popular figure in Glasgow as were Audrey Wise in Preston and former Speaker Betty Boothroyd in West Bromwich.

The has also been a bitter internal dispute in Preston where candidate Mark Hendrick, a Blair loyalist, only narrowly beat Mrs Wise's daughter Valerie to the candidacy.

So Tony Blair knows he has to fight for every vote in all these polls and that the results will give him the clearest possible signal about what voters currently think of his government.