By Andrew Marr BBC News political editor

If public sector workers are a touch confused about how the government regards them, it's hardly surprising.

Tony Blair has "scars on his back" but a welcoming grin on his face. He lauds some public servants as heroes and others as wreckers.

We are used to ministerial anger about strikes, most recently the RMT stoppages on South West Trains, and to Mr Blair's insistence that private money and management are needed to deliver better public services.

But in his Cardiff speech on Sunday Mr Blair was going it some. He managed to outrage mainstream, moderate union figures like Bill Morris of the Transport and General Workers' Union and TUC general secretary John Monks, who were genuinely surprised and hurt.

'Wreckers'

So what's going on? Was it simply a poorly-judged speech by a leader increasingly worried and frustrated by the slow progress of reform? Or was it an entirely intentional provocation?

It is not only union leaders who are confused and angry; many of their members are, too

Andrew Marr

Monday morning's Downing Street briefing suggested the latter.

Mr Blair's spokesman had a perfect opportunity to play down his words and pour a little oil on trade union sensitivities. He didn't.

The 'wreckers', he said, were all those who were against either extra funding or reform - which suggests both Tories and union leaders: no flinching, no second thoughts.

Public services

It comes at the start of a week likely to be dominated by argument about how far, if at all, the Labour government has made any progress on the public services.

An Ofsted report is expected to single out an increase in teaching quality and new NHS staffing figures are likely to show some improvement there too.

But on the other side there is a crucial meeting of the London Transport Board which will help decide what happens on the Government's proposals for a public-private partnership for the Tube; while the RMT has announced further strikes in the south-east of England.

To understand Mr Blair's strategy it is essential to remember that he is not hugely interested in the reaction of trade union leaders to what he says.

Like many prime ministers before him, he thinks he understands their members at least as well as they do; but above all, he is talking to voters, users of public services.

Investment

Many economists believe that April's Budget will have to introduce higher taxes to pay for the massive, if belated, increases in public service investment that Mr Blair and Gordon Brown have announced.

If that is so, then the prime minister will want to be clearly established in voters' minds as a hard-line reformer, determined to spend their money shrewdly and carefully.

These attacks on "wreckers" would therefore be part of a process of softening up the public for higher taxes...and Mr Blair would expect his union critics to calm down quickly when they read the lesson of the Budget.

Activists

So much for the tactical thinking - at least according to Labour insiders.

Attack the minority of diehard anti-private sector activists while lavishing extra resources - including substantial pay increases - on the majority of people working in state schools and hospitals.

The voters are reassured that this is not a return to Old Labour tax-and-spend and put up, however grumpily, with paying the bills.

The dangers, however, are obvious.

It is not only union leaders who are confused and angry; many of their members are, too.

And as Mr Blair himself has said, without the support of public sector workers, all his hopes for better services will turn to dust.