Hillary Clinton adopted a softer tone towards Barack Obama before today’s South Carolina Democratic primary, which polls suggested that he was likely to win.

“All of us need to take a deep breath here,” she said yesterday, after a week scarred by acrimony with the Obama campaign. Mrs Clinton took on the role of “good cop” in TV interviews, even as aides confirmed that her husband would continue to play “bad cop”.

She said: “I have tried to make it clear that this election has to be about the future. Our campaigns have to stay focused on what the legitimate differences are.”

With Mr Obama leading in polls Mrs Clinton’s campaign is managing expectations, suggesting that her rival’s strength among the black voters — who will account for about half the turnout — should guarantee him victory.

She has spent much of the week preparing for battles in big states such as California, New Jersey and New York, which vote on “Super Tuesday”, February 5. It has been Bill Clinton’s aggressive style that has featured most prominently in South Carolina, where he is a popular figure with African-Americans.

Mr Obama’s campaign has complained that Mr Clinton’s behaviour is inappropriate for a former President. Mrs Clinton, though, is understood to believe that the benefits of unleashing her husband outweigh the costs.

James Carville, a long-time adviser and friend to the Clintons, said: “Does the President risk going overboard? Sure. But Obama runs a risk of being wussified.”

Challenged about some of the charges laid at Mr Obama’s door — including his “17-year relationship” with Tony Rezko, the Chicago slum landlord, Mrs Clinton said: “I try not to attack first but I have to defend myself. I do have to counterpunch.”

On the NBC Today Show, she was confronted by a photograph showing her standing with Mr Clinton alongside Mr Rezko, who goes on trial for fraud next month. Mrs Clinton appeared unfazed. “I wouldn’t know him if he walked into the door,” she said. Yesterday her campaign held a conference call where it tried turn the spotlight on to the negative attack advertisements being run by Mr Obama, one of which accuses her of being willing to do — or say — anything to win. Mrs Clinton said: “There’s been a lot that’s been said on both sides and some of it has been kind of generated and certainly stoked. That all needs to calm down.”

There are also fewer sharp elbows flying in the Republican race than previously. In a tepid televised debate on Thursday night in Boca Raton, before Florida’s primary on Tuesday, candidates kept most of their scorn for the Clintons.

Mitt Romney, the former Governor of Massachusetts, hinted that he was looking forward to running a general election campaign reminding voters of the scandals that dogged the White House a decade ago. Asked how he would tackle Mrs Clinton’s formidable political machine, he replied: “I frankly can’t wait because the idea of Bill Clinton back in the White House with nothing to do is something I can’t imagine.”

John McCain, who is shown by polls to be locked in a close contest with Mr Romney in Florida, denounced Mrs Clinton for flying the “white flag of surrender” over future military involvement in Iraq.

He is running an advert depicting Mr Romney as John Kerry, the 2004 Democratic nominee, whose windsurfing activities became symbolic of his apparently shifting policy positions. “Where does Mitt Romney stand?” asked the advert. “Whichever way the wind blows.” Mr McCain may have been embarrassed by yesterday’s endorsement from The New York Times, a newspaper regarded by conservatives as a bastion of liberalism.

In the debate he was also asked about remarks from his 95-year-old mother, Roberta, who suggested that he was not being helped by a Republican base that continues to regard some of his maverick stances with suspicion. The party would be “holding their nose [because] they’re going to have to take him”, she said.

Mr McCain laughed and insisted that Republicans supported him in the fight against Islamic extremism and knew he would put his country ahead of his party “every time”.

Mr Giuliani, who has slipped into third place in Florida, a state that he had long since counted on winning, claimed that he had lulled all his rivals into “a false sense of security”.

There was fresh focus yesterday on the fears of recession, which have emerged as crucial issue in Florida. Mr Romney highlighted his business expertise, saying: “The only way to get America on track economically is to have a president who actually understands how the economy works.” Mr McCain suggested that his own record of “making national policy” on the economy in the Senate was probably “more beneficial to the nation” than running a venture capital company like Mr Romney.

Times Recommends

• It’s only Brits who don’t appreciate me, says Blair
• Party’s over for Greek graspers
• White House tightens security for Xmas marathon