Washington (CNN) Republican Senate candidate and former Maricopa County sheriff Joe Arpaio suggested that he would revive the debunked claim that President Barack Obama's birth certificate is fraudulent if he's elected to the Senate.

At a conservative convention last week, Arpaio recalled introducing President Donald Trump at a campaign rally where the former sheriff mentioned illegal immigration and the "birther" theory -- that Obama was not born in the US and therefore was ineligible to be president.

"I don't talk about it anymore, until I become the US senator ... It has something to do with a document," Arpaio said at the Western Conservative Conference in Phoenix, according to a video posted to YouTube Saturday by Tru Conservative TV.

"If I asked you guys — I'm a nothing now, but if I were still the sheriff, I could ask for your birth certificate," he said. "So, I'm kind of dropping that right now."

Arpaio then claimed that he proved "100%" that Obama's birth certificate is a "fake document."