Story highlights Barack Obama stopped by a fundraiser for Doug Applegate, who is challenging Darrell Issa

The President went on a lengthy rant about Issa and GOP presidential nominee Donald Trump

La Jolla, California (CNN) President Barack Obama directed harsh criticism at Rep. Darrell Issa at a fundraiser Sunday in La Jolla, California, claiming the former House Oversight Committee chairman's "primary contribution to the US Congress has been to obstruct and to waste taxpayer dollars on trumped up investigations that have led nowhere."

Issa hit back at Obama, accusing the President of failing to take accountability "for the serious scandals that happened under his watch," in a statement emailed to CNN Monday morning.

"I'm disappointed but not surprised that the president, in a political speech, continues to deny accountability for the serious scandals that happened under his watch where Americans died overseas and veterans have died here at home," Issa said. "You'd be hard pressed to find anyone who thinks I've done too much to hold Washington accountable. I've worked with the administration on good legislation where it was possible, and called out wrongdoing wherever I saw it, and will continue to do so."

Issa later told Fox News: "He's making a big deal over something that I'm a little surprised that he's punching down, but he is."

Obama lashed out at Issa, who after years of challenging the President, is now touting his cooperation with the White House in a campaign mailer featuring an Obama photo. The Democratic candidate challenging Issa for his Southern California district -- Doug Applegate -- was in attendance at the $10,000-a-plate-and-up fundraiser.

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