The annual crop of local authority elections has been overshadowed by the novelty of the first elections to the Scottish and Welsh assemblies on the same day. But the town hall polls will provide a useful barometer on whether Labour can retain the support it won in Middle England and the South at the 1997 general election.
Elections take place in 362 authorities, with 13,000 seats up for grabs in most areas of England (excluding London) as well as for the councils in Scotland and Wales.
Voter apathy is the greatest threat to Mr Blair as he faces his biggest electoral test since becoming Prime Minister. Ironically, the Labour Party may suffer because the public is broadly content with the Government. "People are not attacking us but we will have trouble getting them out to vote," said one.
A new-style Labour election broadcast to be shown tonight ends with the slogan: "Complacency is the enemy. Keep voting Labour." Divided into five, 30-second commercials, it shows a rich "Yuppie" happy with the Government.
Ministers fear that the turnout in some inner cities will be much lower than the 29 per cent national average in last year's local elections, and that Labour will be hit because the Tories will persuade more of their supporters to vote.
"My greatest concern is that people will think it doesn't matter if they don't go and vote," Margaret Beckett, the Commons Leader and Labour's campaigns co-ordinator, said on GMTV's Sunday Programme yesterday.
The expected apathy may encourage Mr Blair to speed his reforms to tackle the problem of "one-party states" being elected on such a low turnout. Ideas include more directly elected mayors, local referendums on big decisions and council tax levels and eventually the use of proportional representation in council polls.
And yet ministers may be partly to blame for the local "democratic deficit": they are fighting the council elections on the record of the Blair government, rather than that of Labour-run authorities.
Labour is bound to suffer overall losses on 6 May because the party did well when most of the seats being contested were last fought in 1995. In contrast, the Tories' 25 per cent of the national vote was their worst performance in any election.
Labour is bracing itself for losses of about 1,200 seats and fears it may suffer a backlash over allegations of sleaze and inefficiency levelled at Labour councils - the main plank in the Tory campaign.
Mr Blair's party is vulnerable in Sheffield, Trafford, Kirklees, Calderdale, Milton Keynes, Bromsgrove, South Ribble, Gedling and five district councils in Hertfordshire.
However, the stakes are higher for William Hague than for Mr Blair, whose reputation rests more on the outcome of the Kosovo crisis. Mr Hague needs to gain 1,000 seats to kill off rumbles of discontent inside his party about his leadership.
Like Labour, the Tories are deliberately playing down their prospects, in the hope that their spin-doctors can persuade the media their party has triumphed on the night. Tory officials talk of gaining between 300 and 500 seats, pointing out that in the opinion polls Labour has widened the gap between the two parties since the general election.
However, in the first 27 by-elections held this year, Labour won 36 per cent of the votes cast and the Tories 34 per cent. This suggests Mr Hague should be looking for gains of between 1,300 and 1,400 seats, according to Colin Rallings and Michael Thrasher at the University of Plymouth, who are the leading number-crunchers for town hall elections.
The Liberal Democrats did well in 1995 and so may lose between 100 and 200 seats this time, but should be able to celebrate a big prize by capturing the once-solid Labour stronghold of Sheffield.
Paddy Ashdown's party may lose its status as the second party of local government behind Labour: although the Tories have slightly more councillors, the Liberal Democrats control more councils.
The spin-doctors will work overtime on 6 May and the following morning, picking out the most advantageous points from what will be a mixed bag of results. The bad news for Mr Hague is that Labour may hold the trump card: Mr Blair may be able to proclaim the best local election performance by a government in mid-term.