The Pima County Sheriff's Department did not immediately respond to a request for comment.
Humphries said the threats have coincided with Saturday's shooting and began nearly right away.
"We had people say, 'too bad it wasn't your family that was killed,'" Humphries told me. Other angry calls have come in as well. "'The blood of that little girl on your hands,'" Humphries recalled one message saying.
But it was a new call that came in this week that Humphries said had him staying out of public view for a while.
"It was something like 'we hate you and we're going to stand against you and we're going to use our First and Second Amendment rights to stop you,'" Humphries told me.
Humphries said he doubted that anything would actually come of the threats, which aren't the first Humphries said he's has received since founding the Tucson tea party group back in 2009. He had to switch to an unlisted phone number, he said, after a number of "crazy" calls came in during the height of the campaign last year.
Humphries was reluctant to talk about the threats he's received, saying he didn't want to come off as though the was trying to steal the spotlight from the grieving families. One of Humphries' neighbors was shot on Saturday, and he said the event has hit him very hard personally.
"I don't want to whine," Humphries told me when I asked about the phone calls. "Obviously you step into the arena you're going to take hits."
But with the city still on edge after Saturday's shooting, Humphries said he understood why the threats have the deputies -- and Humphries -- more worried than they usually would be.
"The chances are there would be no problem," he said. "But I have a wife and kids."
Though he won't be in attendance this evening, Humphries says he's glad Obama is coming to Tucson.
"I've been very impressed with the way he's handled things so far," he said. Humphries said the president has struck "the right tone" in the aftermath of the shooting and he hopes the president's visit will put a pause in the political debate that has continued after the deadly shooting spree Saturday.
"From the way he's handled it so far he's been really impressive," Humprhies said of Obama.