The Chancellor, set to become Prime Minister as soon as next year, has been targeted by David Cameron and his resurgent Conservatives.
Aware that it is Mr Brown he will fight at the next election, Mr Cameron has attempted to paint the Chancellor as a closet socialist, a "roadblock to reform" in clear contrast with Mr Blair.
The Tory tactic has been helped by Mr Brown's history of playing to the Labour left and hinting that he is closer to them than Mr Blair.
Now, the Chancellor is trying to reposition himself by stressing his own modernising credentials.
In the latest of a series of interviews, Mr Brown last night promised to press ahead with Mr Blair's plans for public service reform and identity cards.
"My message is, reform is going to continue," Mr Brown told the BBC.
"That will mean continued reform, continued modernisation, if necessary an intensification of reform."
Some left-wing MPs hope Mr Brown is less than convinced by the case for ID cards, but the Chancellor bluntly dashed that hope.
"I want the toughest of security in defence of people's liberty," he said.
Mr Brown also made a direct attack on Mr Cameron, who has been busily ditching long-standing Tory policies in a bid to claim the political centre-ground.
"The problem as I see it is, we have someone who is saying I'm Conservative to the core one day, I'm the inheritor of New Labour the next day, I'm a Liberal the next day," said Mr Brown, deriding Mr Cameron's recent moves as a "glib PR exercise".