克林顿力挺奥巴马 称其为中产阶级救星

Bill Clinton will tell struggling Americans nostalgic for his presidency that Barack Obama is still the man to rebuild the middle class, while Mitt Romney would hand ruinous tax cuts to the rich.

In a speech closing the second night of the Democratic convention, the former president will warn voters that Mr Romney would repeat the economic policies that "got us in trouble in the first place".

"President Obama has a plan to rebuild America from the ground up," he said in a campaign video billed by Obama aides as a preview of his remarks. "It only works if there is a strong middle class. That's what happened when I was president. We need to keep going with his plan." Mr Clinton is expected to contrast Mr Obama's priorities of education and training with Mr Romney's pledge to cut income taxes and reverse the regulation of the financial sector since the 2008 crisis.

Mr Obama has worked to repair the damage to their relationship caused by his defeat of the former president's wife, Hillary, in 2008's bitter party primary, by seeking his counsel over rounds of golf.

In June, Mr Clinton appeared to say that income tax cuts introduced by President George W. Bush, which are due to expire at the end of the year, should be extended for all to prevent an economic slump. Mr Obama opposes extending the tax cuts for high earners. Mr Clinton later insisted they were in agreement.

Jeffrey Lord, a historian and former aide to Ronald Reagan, said the only precedent for Mr Clinton's role in recent memory was the speech given by Mr Reagan as a "private citizen" to the 1992 Republican convention, as his successor, George H.W. Bush, struggled to defend his presidency against Mr Clinton.

"It was for exactly the same reason," Mr Lord told the reporters.

"Obama needs Clinton just as Bush needed Reagan. But even Reagan couldn't save Bush – and I'm not sure Clinton can save Obama."