Washington  - Republican White House hopeful John McCain made his sharpest divide yet from US President George W Bush, declaring in a new television advertisement Tuesday that the state of the nation has worsened over the last four years.

"Washington's broken. John McCain knows it," a narrator says in the new ad. "We're worse off than we were four years ago."

The campaign ad portrays McCain as the "original maverick" and highlights his reputation as an independent during nearly 30 years in Congress, representing the state of Arizona.

McCain has bucked his own centre-right Republican Party on issues including climate change and immigration and led efforts to reform campaign-finance laws.

Democratic rival Barack Obama has regularly characterized McCain as running for "Bush's third term," pointing to much of his economic policy and support for keeping US troops in Iraq.

Bush's approval rating has hovered around 30 per cent in the last year, but polls nevertheless place McCain in a close race with Obama ahead of the November general elections.

McCain has made a limited amount of campaign appearances with Bush since picking up the president's formal endorsement in March. (dpa)