(AP Photo/Carolyn Kaster)

Lending his fundraising prowess to President Obama's re-election campaign, Bill Clinton warned top donors in New York tonight that Mitt Romney would be "calamitous for our country and the world."

"The politics is wrong on the Republican side, the economics are crazy," Clinton said at a fundraiser at the Upper East Side home of billionaire hedge fund manager Marc Lasry.

Just one week after praising Mitt Romney's "sterling business career," Clinton argued that Republicans' "economics are wrong-headed and their politics are worse."

"The Republican Congress and their nominee for President, Governor Romney, have adopted Europe's economic policies," Clinton said. "Their economic policy is austerity and unemployment now, and then a long term budget that would explode the debt when the economy recovers so the interest rates would be so high nobody would be able to do anything."

Instead, Clinton said the president's policies provide "job growth now, and long term budget restraint."

Obama has the "right economic policy and the right political approach," he said.

The president "has good politics, he's got a good record, he's made the best of a very challenging situation, he deserves to be reelected," Clinton concluded, before joking that he "has a pretty good secretary of state too."

On the heels of Friday's disappointing jobs report, Obama continued to argue that the economy is the central issue of the campaign but admitted that "when things are tough, you're willing to try just about anything even if you've seen it before."

The president was adamant that going forward, his campaign needs to get a "clear message out about how we intend to grow the middle class, how we're going to create jobs, and how our positions are squarely in the center of America's traditions."

"We're not the ones who've changed. What has changed is the Republican Party," Obama said. "They have run from a preference for market-based solutions to an absolutism when it comes to the marketplace, a belief that all regulations are bad. That government has no role to play."

The private fundraiser kicked off a trio of campaign events in New York City tonight, which are expected to add upwards of $3.6 million to the president's re-election coffers.