PHOENIX, Ariz. -- Arizona Democrats will have to keep looking for a strong Senate candidate.

Homeland Security Secretary Janet Napolitano doesn't sound like she's interested. The popular former governor was given a warm reception by students and faculty at Arizona State University's Tempe campus Thursday.

After a speech focused on border security, she took questions from the audience.

Asked which Republican she thought was more beatable, John McCain or J.D. Hayworth, Napolitano paused. "Next!" she said, with a wry smile.

Napolitano is widely seen as the Democrats' best hope for picking up the state's Senate seat.