The spot, "Lived It," compares Carmona's past working as a combat veteran and in law enforcement with Flake's record on veterans' issues in Congress. The ad is the third from Carmona that features clips of him from when he was in the Army, during Vietnam, indicating his campaign believes this is one of its strongest selling points.

"In the Senate, he'll support our veterans, because he's lived it," a voiceover says.

In contrast, the ad calls Flake "part of the problem," because of what it characterizes as votes to cut benefits for veterans and against a combat bonus for troops.

"Congressman Jeff FlakeJeffrey (Jeff) Lane FlakeMcCain rips Trump for attacks on press Bipartisan group to introduce DACA bill in House Flake's anti-Trump speech will make a lot of noise, but not much sense MORE helps himself — not us," a voiceover says.

But Flake campaign spokesman Andrew Wilder pushed back against the add, pointing to over 80 pro-veteran bills Flake has supported during his tenure to illustrate what he said was Carmona's "cherry-picking" in the ad.

“Democrat Richard Carmona uses the old liberal playbook by cherry-picking a few votes and ignoring scores of veterans bills that Jeff Flake has supported.  Jeff Flake has a strong record of standing up for our nation’s servicemen and women, and that's a record he will continue in the Senate.  Unable to talk about issues and desperate to gain traction, Richard Carmona has adopted the negative, partisan tactics and tone he decried when he entered the race," he said.

Flake has already released a similarly negative ad, comparing his record and Carmona's on Obama's healthcare law and party support. Flake hopes that tying Carmona to an unpopular Democratic president and his policies will help him win in deep-red Arizona, but Carmona's campaign has indicated that it believes two aspects of his background — his work as surgeon general under President George W. Bush and his time in the military — could win points for him.

Watch the ad:

--This post was published at 8 a.m. and updated at 12:04 p.m.