The Arizona Republic, Deirdre Hamill/AP Photo

A sheriff who has gained notoriety as an outspoken opponent of illegal immigration has stepped down from his post as the Romney campaign's Arizona co-chair after allegations surfaced that he threatened his ex-boyfriend with deportation.

Paul Babeu, 43, who serves as  sheriff in Pinal County in Southern Arizona, rose to prominence when the then-first term sheriff appeared in campaign advertisements with John McCain in 2010. The pair walked along a border fence, which McCain had vowed to complete.  Babeu tells him:  "Senator, you're one of us."

At a press conference today, Babeu responded to allegations levied against him by his former boyfriend that were first published in the Phoenix New Times. The man, who is undocumented, was only identified as Jose. He alleged Babeu threatened him with deportation after he wouldn't agree to never disclose their relationship.

"It's blatantly, completely false," Babeu said. "I never believed he was less legal than I or you are."

But texts obtained by the newspaper that were traced back to Babeu's phone number told a different story.

"You can never have business after this and you will harm me and many others in the process . . . including yourself & your family," Babeu allegedly wrote on Sept. 4, 2011.

Besides serving as sheriff, Babeu is currently pursuing a congressional bid.