The owner of a Colorado auto dealership has gotten international attention after putting up a controversial billboard about President Barack Obama.

Phil Wolf, the man behind the billboard and Wolf Interstate Leasing and Sales, says he wishes he was better prepared for the flood of reaction to the sign.

The sign asks if President Obama is a terrorist and if he’s really an American citizen by birth.

Part of the sign also references the recent tragedy at Fort Hood.

The question of Obama’s citizenship has been an issue since early in his presidential campaign.

Hawaiian officials have inspected his original birth certificate, proving he was born in the United States.

The conspiracy theory has persisted in part because Hawaiian officials won’t release the president’s, or anyone else’s, original birth certificate.

There’s other evidence out there that he was indeed born in Hawaii – birth announcements in both of Honolulu’s major newspapers in August 1961, and a teacher who says she discussed his birth with Dr. Rodney West, the obstetrician who delivered Obama.

Wolf says he initially drew the billboard on a napkin and then had an artist paint it.

The sign, which was completed Friday, is visible to drivers on Interstate 70.

“I can’t say I expected everything that’s been going on with the responses we got,” Wolf said.

He says his business has been overwhelmed with phone calls.

Some callers have threatened both Wolf and his employees.

Wolf says he’s accepting the risk and the backlash he may receive.

“We’ve had calls as far as Canada to Florida. We’ve had calls all over the country,” Wolf said. “I didn’t expect employees to leave scared going home from work that were threatened, death threats and attempts to bomb the place. It’s been pretty crazy out there.”

Wolf says his main reason for creating this billboard was to bring attention to the men and women who died at Fort Hood and to ask questions about Obama he says haven’t been answered.

“It may be a little scattered. It says several things. It brings us several questions and I think they got to be answered,” Wolf said.

The Anti-Defamation League says its problem with Wolf’s billboard is that it uses religious imagery to stereotype all Muslims, and the organization wants it removed.

“It was the religious message that drew our attention,” Joyce Rubin with the ADL said. “By linking an image of a turban and a robe and a reference to the Fort Hood tragedy, the suggestion was made that this was somehow a Muslim responsibility and not the responsibility of an individual.”

Wolf’s billboard has drawn both criticism and support since it went up.

“I think the sign’s great. It’s showing what is true,” Leigh Ann Cross said.

“There’s enough intolerance and hatred going around, We shouldn’t have it right here in Wheat Ridge as well,” Maggie Couch, a woman who came out to protest the sign, said.

According to Wheat Ridge Police, Saturday afternoon a man was cited for disorderly conduct and criminal mischief after he allegedly threw a wooden pallet at a protest banner.

The man told police it was an accident when he tripped and fell.

Wolf says while he says he doesn’t want to risk the health of his business or employees, he is in no hurry to take it down.

“I believe in it enough. I believe in America enough… that I think it’s worth the risk,” he said.