Perry (Iowa), Jan. 1: Barack Obama unleashed a blistering attack on his Democrat rival Hillary Clinton yesterday, branding her “just like George W Bush”.

The cutting comparison came as he launched a last-ditch push to win over Democrats in Iowa, who vote on Thursday in their caucuses, the first stage of the presidential nomination process.

Now, his lofty rhetoric about hope and change is laced with sharp, sarcastic jabs at Hillary and her husband Bill, who have sought to paint him as a naïve lightweight who doesn’t have the stomach for a fight.

At a Des Moines rally that drew in more than 1,000 people despite freezing weather, Obama abandoned his previous timidity and, while not mentioning her by name, aimed barbs straight at the former First Lady. “We can’t afford a politics that’s all about terrorism and ripping people down rather than lifting a country up,” he said.

“We can’t afford a politics based on fear that leaves politicians to think the only way they can look tough on national security is to vote and act and talk just like George W Bush.”

Obama is locked in a three-way struggle with Hillary and John Edwards in Iowa. Polls, which are notoriously unreliable in the Midwestern state, indicate Hillary might have edged just ahead in the past week.

Bill Clinton, now campaigning in Iowa for his wife every day, has raised the spectre of another September 11 style attack and stated that only Hillary had the experience to deal with a terrorist atrocity.

Obama blasted back by suggesting that this was reminiscent of the tactics of Bush and Vice-President Dick Cheney in 2004 and amounted to “using 9/11 as a way to scare up votes”.

The slap at Hillary — who voted to authorise the Iraq war — was no accident. Yesterday, at a smaller rally in rural Perry attended by about 250 people, Obama used almost exactly the same words.

When asked by The Daily Telegraph about the increasing sharpness of Obama’s words, David Axelrod, his chief strategist, said: “I don’t think they were sharp. I think they were well chosen.”

He added that Hillary was “100 per cent known” but “70 cent or more of voters in this state have consistently chosen other alternatives so there’s obviously a market for something different out there.”

The Obama campaign has been angered by the negative attacks from Clinton operatives, most notably the suggestion — widely seen as a racial smear — that he had been a cocaine dealer.

The Illinois senator took on Bill Clinton directly, disputing the former President’s contention that a vote for Obama would be to “roll the dice” on America’s future.