Democratic U.S. Senate candidate Richard Carmona focuses on the health-care system.

The hot topic got an immediate response from his opponent's campaign.

A spokesman for Republican candidate Jeff Flake accuses Carmona of running from his support of the Affordable Care Act. The ad brought similar condemnation from the National Republican Senatorial Committee.

In August, Carmona told CNBC that the law needs more preventive care and a more “robust business model.”

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