"Cross dressing" between different parties over policy has replaced the era of "tribal" politics, Tony Blair has told Rupert Murdoch's media chiefs.
Mr Blair is on a four-day trip to California
Mr Blair told News Corporation's annual conference in California that most policy prescriptions now crossed "traditional left/right lines".
He said the change explained why he had been attacked by right and left-wingers over NHS reforms and tackling crime.
But his fear was "not being radical enough" in a fast-changing world.
"In these times, caution is error; to hesitate is to lose; yet many of these decisions are acutely, finely balanced," he said.
Mr Blair said the new political climate, where old divisions had gone, could be confusing for politicians.
"Basic values, attitudes to the positive role of government, social objectives - these still do divide along familiar party lines," he told the media executives at Pebble Beach.
"But on policy the cross-dressing is rampant and is a feature of modern politics that will stay. The era of tribal political leadership is over."
He said he had introduced new measures to tackle anti-social behaviour because he believed the problem hit the poorest and most vulnerable worst.
"Much of the opposition came from those normally to the right of me who thought it a breach of our traditional British civil liberties," he said.
"I am attacked from the left for introducing market mechanisms into the NHS. But for me it is an issue of equality. Patient choice should not be restricted only to those who can afford to pay for their health care.
"And, of course, foreign policy is now creating strange bed fellows across the piece."
The prime minister said there was a new division between "open and closed" politics which was almost as pivotal as the traditional right-left split.
"The response to globalisation can be free trade, open markets, investment in the means of competition: education, science, technology," he said.
"Or it can be protectionism, tariffs, tight labour market regulation, resistance to foreign takeovers."
He said every country was "riven" with debates about migration - whether to treat it as an infusion of new blood and ideas or as a threat to national identity.
"In this battle - 'open versus closed' - those on the "open" side of the argument will meet fierce opposition," he said.
"Yet the 'closed' side of the argument in truth has nothing to offer a nation except the delusion that the tide of change can be turned back; or alternatively a weaker version of the same delusion, namely that hard choices can just be evaded."
Mr Blair insisted he would not change his foreign policy stance, calling for ideas to combat global terrorism.
"I am sometimes taken to task for being too ambitious in the radical nature of the policy changes I am seeking," he said.
"I always have the opposite worry: not being radical enough."