When President Franklin D. Roosevelt took office in the depths of the Great Depression in 1933, he launched an ambitious legislative program in the first 100 days.  Ever since, initial accomplishments of new U.S. presidents have been measured in the same time span.   And President-elect Barack Obama will have both leftover issues from the Bush administration and his own campaign agenda to put before Congress in those first days when he takes office in January.

President-elect Obama makes an opening statement on the economy during a press conference in Chicago, 07 Nov 2008

At his first news conference since winning the White House, President-elect Barack Obama said his top priority is getting Congress to act immediately to address a range of economic problems.

President-elect Obama said, "A particularly urgent priority is a further extension of unemployment insurance benefits for workers who cannot find work in the increasingly weak economy. A fiscal stimulus plan that will jump-start economic growth is long overdue. I've talked about it during the last few months of the campaign - we should get it done. We [also] have to address the spreading impact of the financial crisis on other sectors of our economy."

Presidents can set an agenda, as they do every year in the State of the Union address.  

But they cannot order Congress to enact what they demand, as explained by Brian Darling, at The Heritage Foundation in Washington. 

"The president actually does not have all that much power to implement their [presidents'] agenda," he said. "They can bring measures to Congress. They can ask that Congress pass ideas like a middle-class tax cut. But then Congress has the opportunity to write that legislation, to amend that legislation, and then pass that legislation in any form they see fit before it comes back to the president [to either sign it into law or veto it.]”

The US Capitol, home to the US Senate and House of Representatives

In moving his agenda through Congress, Mr. Obama will enjoy enlarged Democratic Party majorities in both the Senate and the House of Representatives. History professor Allan Lichtman  at American University says that increased support will be critical to the new president for addressing today's serious problems. 

"The lessons from [previous] first term presidencies are [that] you have got to implement your changes quickly," he said. "You have a narrow window of opportunity [to enact legislation from your agenda]. [President Franklin D.] Roosevelt had his 100 days. [President] Ronald Reagan implemented his 'Reagan Revolution' in less than a year. You do not have the luxury of time, particularly in the midst of a crisis this severe."

Despite those Senate and House Democratic majorities, Mr. Obama will still have the opposition Republicans to deal with. And Nathan Gonzales, the Senior Editor for the Rothenberg Political Report  says it is not clear yet whether Republicans will cooperate or obstruct. 

"There is going to be a wait-and-see period, I think, for the Republican Party where they regroup after this election, watch the Democrats and see what they do - see what they do wrong in the eyes of the Republicans, and then, stake out their next set of issues,” he said.

Mr. Obama's candidacy ignited enthusiasm in many places around the globe.  
Experts say he will focus some of his attention on international affairs in the first 100 days, as Georgetown University government professor Mark Rom  points out. 

"He also, I anticipate, will reach out internationally to try to rebuild the stature of America in the world, by meeting with foreign leaders - not without precondition - but will meet with them in ways to suggest that the U.S. is open to more multi-lateral cooperation than in the past [during the Bush administration], and try to restore America's moral standing in the world," he said.