The news conference is expected to be held at 4 p.m. in Phoenix, Arizona.
Arpaio, the sheriff of Maricopa County, has long been a vocal proponent of the "birther" conspiracy theory that questions whether Obama was born in the United States. In 2012, Arpaio claimed he had "probable cause" to show that the President's birth certificate was a forgery and held a news conference where he alleged that there were secret codes hidden in the document.
Following President-elect Donald Trump's cursory statement in September acknowledging that he believes Obama was born in the United States and taking credit for the President releasing his longform birth certificate, Arpaio distanced himself from the then-candidate and pledged to continue pushing the conspiracy theory.
He was also quick to take advantage of Trump's brevity.
“He didn’t say the document was legitimate. He didn’t go that route,” Arpaio said just days later, as reported by Politico. “It didn’t bother me.”