Tony Blair entered Britain's close-fought election campaign on Tuesday, seeking to work his charm on voters tempted to desert the Labour Party 13 years after he led it to power.

The former prime minister propelled Labour to three electoral victories over the Conservatives from 1997. But he resigned in mid-term in 2007 to make way for Gordon Brown, who had been his chancellor for a decade.

Brown is seeking to win an unprecedented fourth successive Labour term in office in an election expected on May 6.

Drafting in Blair is a risky strategy for Labour. The ex-prime minister is a charismatic campaigner, but many voters are still angry with him for leading Britain into war in Iraq.

Labour is trailing the Conservatives in the opinion polls although the gap has narrowed since January. Most polls suggest the result could be a "hung parliament" in which no party has an overall majority. This could allow Brown to stay in power at the head of a minority government.

Returning to the constituency of Sedgefield in northeastern England which he represented in parliament for 24 years, Blair praised Brown's handling of the economic crisis and hailed his "experience, judgement and boldness."

"It required leadership and Gordon Brown supplied it," Blair told enthusiastic party activists at the local Labour Club.

The Conservatives hit back by deriding Blair for getting rich on the lucrative lecture circuit since he stepped down.

"It's nice to see him making a speech that nobody is paying for," Conservative leader David Cameron told Sky News.

>Blair now does consultancy and public speaking as well as promoting Palestinian economic development on behalf the Quartet of major powers. He has also launched initiatives on faith, sports, African governance and climate change.

"ELECTORAL MAGIC?"

Blair and Brown had a uniquely close but fraught partnership at the top of British politics for a decade. It was an open secret that Blair had promised Brown he would hand over the reins at some point, and this caused unending tension.

Brown, who has had a bumpy ride as prime minister, is now playing up his record on economic management, arguing that he took bold decisions during the 2008 credit crunch that averted a total collapse of the financial sector and the economy.

The Conservatives blame Brown for Britain's huge deficit and for leading the country into a deep recession.

Credited with broadening Labour's appeal beyond its traditional left-wing working class supporters, Blair is widely seen as a more accomplished public performer than Brown.

But Blair was deeply unpopular by the time he left office because of his decision to join the United States in invading Iraq based on the supposed threat from Saddam Hussein's weapons of mass destruction, which turned out not to exist.

As his car pulled up outside the Labour Club in Sedgefield, Blair was met by a small crowd of protesters brandishing placards that read "Bliar, War Criminal."

Despite bitter memories of Iraq, Andrew Hawkins of pollsters ComRes said deploying Blair was a risk worth taking for Labour.

"Tony Blair had a little bit of electoral magic that Brown could do with trying to conjure up again," he told Reuters.

Hawkins said many of the people who had voted for Labour in the last three elections had done so because of Blair's centrist appeal, but they were now wavering. Blair could help bring those people back into the Labour fold, he said.

(Writing and additional reporting by Estelle Shirbon; Editing by Dominic Evans and Paul Taylor)