U.S. President Barack Obama is getting ready for this week's Democratic National Convention, rallying support from blue collar workers in the nation's heartland.

In a Labor Day holiday address, Mr. Obama told unionized auto workers Monday in Toledo, Ohio that he's willing to bet on them “any day of the week.”

The Democratic National Convention – where Mr. Obama will be formally nominated for a second term – opens Tuesday in Charlotte, North Carolina.

Later Monday, the president will visit Louisiana to view damage caused by Hurricane Isaac last week.

Republican challenger Mitt Romney said Labor Day was “a chance to celebrate the strong American work ethic.” But he said that for many jobless Americans it is “another day of worrying” when their next paycheck will come.

Many voters say the key issue for them remains the country's struggling economy. Surveys of eligible voters show Mr. Obama in a virtual tie with Mr. Romney.