LONDON — President-elect Barack Obama assumes power (Tuesday) at a time when the United States faces huge problems at home and abroad. Americans and people all around the world are looking to him for leadership and a return to the ideals set out in the U.S. Constitution.

The problems he faces are so numerous and difficult that it is inevitable that some of his supporters will be disappointed. Even the president of the world's only superpower has limited authority. Congress will need to be convinced that his proposals are appropriate.

His first task will be to kick-start the economy. His initial proposals are ambitious, but may not be enough and Congress will not be rushed. International confidence in the dollar and U.S. Treasury bonds has so far remained reasonably stable not least because there are doubts about the strength of alternatives. Recovery of the U.S. economy will be crucial to America's ability to deal effectively with the challenges facing the country abroad.