A combination photographs shows US President Barack Obama addresses his election night victory rally in Chicago, and Republican presidential nominee Mitt Romney pauses as he delivers his concession speech in Boston, Massachusetts, respectively, Nov 7, 2012. [Photo/Agencies]

CHICAGO - US President Barack Obama early Wednesday morning said in his victory speech he looked forward to solving the country's problems with Republicans.

Speaking at his Chicago campaign headquarters after winning Tuesday's presidential elections against Republican challenger Mitt Romney, Obama said he was returning to the White House more determined and inspired, promising to work with leaders of both parties to reduce deficit, fix tax code and work on immigration reform.

Obama also said he wanted to meet the former Massachusetts governor to discuss ways to "move this country forward".

Before Obama spoke, Romney conceded defeat at his Boston campgaign headquarters.

Romney said in this "time of great challenges for America," Republicans and Democrats should work together to avoid "partisan bickering and political posturing," saying leaders should reach across the aisles to solve the nation's myriad of problems.

"We look to Democrats and Republicans in government at all levels to put the people before the politics," said Romney.

After the election results were known, House Speaker John Boehner said in a statement that the mandate of the reelection of Obama and a GOP majority in the House is "a mandate for both parties to find common ground and take steps together to help our economy grow and create jobs".

Obama is facing pressing issues of the so-called fiscal cliff even before he begins his second term next year. The sweeping tax cuts of the Bush era will expire and painful automatic cuts will set in next year if Congress fails to act, threatening to plunge the country into recession again.