CHICAGO– Barack Obama said on Saturday that, with the long US presidential election campaign over, now was the time for Americans to put aside political differences and work together to solve the economic crisis.

US President-elect Barack Obama answers a journalist's question during his first press conference following his election victory in Chicago, November 7, 2008. [Agencies]

Obama, a Democrat who won a decisive victory against Republican John McCain in Tuesday's election to become the first black US president as of January 20, vowed to seek unity.

He noted Republican President George W. Bush and first lady Laura Bush had invited Obama and his wife Michelle to the White House on Monday and that the Bushes had offered to do all they could to help with Obama's transition.

"This speaks to a fundamental recognition that here in America we can compete vigorously in elections and challenge each other's ideas, yet come together in service of a common purpose once the voting is done," Obama said in the Democratic Party's weekly radio address.