US President Obama Monday hit the campaign trail ahead of looming midterm legislative elections, delivering a rousing speech in Wisconsin aimed at reinvigorating the wilted Democratic Party base, dpa reported.
Obama lashed out at Republicans for helping to "devastate our middle class and drive our economy into a ditch" and expressed outrage at their "nerve" for now asking for the keys back.
"I don't want to give them the keys back. They don't know how to drive," Obama said to roaring cheers.
Obama's Democratic Party faces major challenges in hanging on to control of the US Congress in November 2 elections, largely regarded as a referendum on a president's performance.
Aided by persistent high unemployment of 9.6 per cent and sluggish jobs recovery, Republicans have armed their political quivers with barbs and fears about Obama's failing performance on the economy.
But Obama, whose popularity rating has fallen to 45 per cent, showed some of the feisty spirit that inspired crowds and got him elected in 2008 as the country's first African-American president.
Obama urged the crowd not to give in to cynicism or doubt, and vowed to "make this case across the country ... from now until November."
"We can strengthen our middle class and make this economy work again," Obama said.
Labor Day, always the first Monday in September, marks the traditional start of election campaigning, as voters wake up from the summer doldrums, send children back to school and begin focusing on issues.
In Milwaukee, Wisconsin, Obama announced a six-year 50- billion-dollar plan to to rehabilitate the nation's transportation infrastructure and provide more jobs. The plan calls to rebuild more than 240,000 kilometres of roads and expand and maintain 6,400 kilometres of rail lines.
On Wednesday, in Cleveland, Ohio, heart of the so-called rust belt, Obama is expected to call for a 100-billion-dollar tax credit to increase and extend benefits for research and development, the Washington Post reported.
The tax credit and infrastructure programmes are aimed at helping the US economy as it struggles to recover from the worst recession in more than six decades.
Republicans charge that Obama has dropped the ball on the economy and spent too much money on stimulus plans that have failed to ease the jobless rate.
Shortly after Obama took office in early 2009, Congress passed the 787-billion-dollar stimulus plan, and, while unemployment has fallen somewhat since then, analysts are worried that the country is headed into a "double-dip" recession.