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PHILADELPHIA -- U.S. Sen. Al Franken leaned on his comedy roots in a short speech to the Democratic National Convention on Monday night made up largely of ridicule for Republican candidate Donald Trump.

"I'm Al Franken – Minnesotan, senator and world renowned expert on right-wing megalomaniacs," Franken said in a prime time speech from the stage of the Wells Fargo Center in Philadelphia. "Rush Limbaugh, Bill O'Reilly and now Donald Trump."

Franken, of course, was a "Saturday Night Live" writer and performer for years before shifting into a career in political satire. His most well-known book of humor bashing conservatives was "Rush Limbaugh is a Big, Fat Idiot."

In 2005, Franken moved back to Minnesota – where he spent his childhood and teenage years – and mounted a political career that saw him elected to the U.S. Senate in 2009 by a historically thin margin. He was reelected much more comfortably in 2014.

Franken joked in his speech that "I got my degree in right-wing megalomania from Trump University." That's the controversial business school established by Trump that is the subject of fraud lawsuits. Franken also mocked the New York real estate tycoon's bankruptcies, saying it featured a 101 class entitled "Leaving Your Friends Holding the Bag."

On Trump's claim of being able to teach business success, Franken added: "If you believe that, I've got some delicious Trump steaks to sell you."

He then pivoted to praise for Democratic candidate Hillary Clinton, whom he talked of knowing for many years.

"I've never met anyone tougher, smart, or ready to lead us forward," Franken said.