The video mocks Cardon for an ad his campaign aired that used a doctored photo of Flake where conservatives who appeared in the photo with Flake were digitally removed and replaced with the likeness of President Obama, making it look as though Flake and Obama had appeared together. The Flake video also hits Cardon on spending, his personal taxes and birtherism.

By Saturday, that video had been pulled from the Flake campaign's website. The video had claimed that Cardon hadn't paid taxes on a company, Eagle Gate Insurance, but the Cardon campaign said the candidate has never had an interest in that company, although a relative of Cardon may have had an interest.

Cardon's spokeswoman said the Flake video had been replaced with a similar video leaving out that accusation, but that Cardon was still waiting for the apology he had requested from Flake's campaign.

The Flake campaign could not immediately be reached for comment on Saturday.

Democrats suggested the ad launch by Flake signaled panic by his campaign, who has seen their lead in the primary of almost 50 points in February shrink to 22 points in May.

Flake's campaign has pointed to a deluge of spending and attack ads from Cardon, who has already injected more than $4 million of his own money into the campaign.

- This story was posted at 3:38 p.m. and has been updated