Former congressman J.D. Hayworth hopes the tea party movement can help him topple one of the Republican Party's best-known politicians.

Hayworth has launched a GOP primary challenge to John McCain less than two years after the Arizona senator lost his bid for the presidency.

The race has quickly become one of the most-watched Senate contests in the country, in part because Hayworth has tried to define himself as a tea party candidate taking on the establishment.

Hayworth has spoken at rallies and neighborhood meetings around the state arguing that he's the best candidate to support tea party values of smaller government, free markets and fiscal responsibility.

McCain's campaign disputes the claim, saying Hayworth supported government expansion as a congressman.