Tony Blair returned to the domestic political stage today with an attack on "vacuous" Tory promises of change.
In his first entry into the pre-election fray, the former prime minister hailed Gordon Brown's leadership, praising his successor for setting Britain on the path to economic recovery.
Speaking to Labour Party activists in his former constituency in Sedgefield, County Durham, Mr Blair sought to contrast Mr Brown's "certain leadership" with the "confusion" at the heart of Conservative policy-making.
The Tories hit back calling for an investigation into the extensive business interests he has built up since leaving office in 2007.
Some Labour supporters were also unhappy at Mr Blair's reappearance on the political scene, warning that he could cost them votes on polling day.
Mr Blair chose Trimdon Labour Club, where he announced his resignation three years ago, as the scene for his return.
He began by highlighting the key role played by Mr Brown in pulling the world back from the brink of disaster when the financial crisis broke in 2008.
"At the moment of peril the world acted. Britain acted. The decision to act required experience, judgment and boldness. It required leadership. Gordon Brown supplied it," he said.
Much of his speech was devoted to an attack on Tory policies and David Cameron's call of "time for a change".
"As I always used to say when some in our ranks urged a mantra of 'time for a change' in 1997, it is the most vacuous slogan in politics," he said.
He said that the election race is narrowing because voters are beginning to ask what exactly the change is that the Tories are offering.
"Think of all the phrases you associate with their leadership, and the phrase 'You know where you are with them' is about the last description you would think of," he said.
"They seem like they haven't made up their mind about where they stand; and so the British public finds it hard to make up its mind about where it stands. In uncertain times, there is a lot to be said for certain leadership."
Mr Blair said that in the run-up to the 1997 general election, as he and Mr Brown had set out a New Labour position across the full range of policies, the question marks over what they stood for had faded.
In contrast, he said, the question mark over the Tories had "gone into bolder print".
"They look like they're either the old Tory Party, but want to hide it; or they're not certain which way to go. But either is not good news," he said.
"On Europe, they've gone right when they should have gone centre; on law and order, they've gone liberal when actually they should have stuck with a traditional Conservative position; and on the economy, they seem to be buffeted this way and that, depending less on where they think the country should be, than on where they think public opinion might be."
He pointed to what he said is the "confusion" in the Tories' economic position, first claiming that cutting the deficit was their "absolute priority", only to turn round and offer a big tax cut as the centrepiece of their policy.
"The benign but still disqualifying explanation is that the policy-makers are confused, not just the policies," he said.
"The less benign one is that one set of policies represents what they believe in; the other, what they think they have to say to win. That's not a confusion, actually, that's a strategy, and the British people deserve to have that strategy exposed before polling day."
Mr Cameron brushed off Mr Blair's attack, quipping: "It is nice to see him making a speech that no one is paying for."
However shadow treasury minister Greg Hands called on the Advisory Committee on Business Appointments - which vets jobs taken on by ministers after they leave office - to investigate Mr Blair's business interests.
In a letter to the committee chairman, Lord Lang of Monckton, he said that Mr Blair appeared not to have registered Windrush Ventures - a company he set up in 2007 - with the committee, as he was supposed to do.
Meanwhile former minister Peter Kilfoyle warned that Mr Blair had become a "negative factor" for Labour.
"I just think that he evokes very strong antagonism, frankly, particularly because of the Iraq War, but not only that - I think that he epitomises all that people see as wrong about New Labour."