NASHVILLE (Reuters) - Democratic presidential candidate Barack Obama said on Tuesday that the United States is in the worst financial crisis of the Great Depression as he opened a debate with Republican rival John McCain.

Obama said the U.S. government should ensure that Wall Street executives do not benefit from bonus payments from failing companies and that if elected, he would seek a tax cut for most Americans.

"We are in the worst financial crisis since the Great Depression, and a lot of you I think are worried about your jobs, your pensions, your retirement accounts," he said.

(Reporting by Steve Holland, Editing by Frances Kerry)