WASHINGTON, Jan. 11 (UPI) -- Sen. Bernie Sanders knocked Donald Trump's "birther" campaign against President Barack Obama, noting that Sanders' own father was born in Poland, and yet "nobody has ever asked me for my birth certificate."
Sanders visited Hoover High School in Des Moines, Iowa, on Monday, stumping for his presidential campaign. In response to a student who asked what Sanders thought about immigrants, the Vermont senator attacked Trump.
"As I mentioned to you earlier, my father was born in Poland. Like Obama, I am the son of an immigrant father. Nobody has ever asked me for my birth certificate. Maybe it's because of the color of my skin being different than Obama's," Sanders, I-Vt., said. CNN reported students cheered the response.
Trump was once one of the loudest voices questioning whether Obama was a natural born U.S. citizen.
"He doesn't have a birth certificate. He may have one, but there's something on that, maybe religion, maybe it says he is a Muslim," Trump told Fox News in 2011. "I don't know. Maybe he doesn't want that."
Obama ended up releasing his long-form birth certificate from Hawaii later that year at the White House Correspondent's Dinner -- with a special call-out for Trump.
"No one is happier -- no one is prouder -- to put this birth certificate matter to rest than The Donald," Obama said. "And that's because he can finally get back to focusing on the issues that matter: Like, did we fake the moon landing? What really happened in Roswell? And where are Biggie and Tupac?"
Trump has revived his "birther" concerns, this time turning them on Sen. Ted Cruz, R-Texas, who was born in Canada. Last week, Cruz released his mother's birth certificate to prove she was born in the United States.