WASHINGTON, April 30 (RIA Novosti) - U.S. President Barack Obama said his administration had "responded to an extraordinary set of economic challenges" in a press conference marking his first 100 days in office.

"Our most urgent task has been to clear away the wreckage, repair the immediate damage to the economy, and do everything we can to prevent a larger collapse. And since the problems we face are all working off each other to feed a vicious economic downturn, we've had no choice but to attack all fronts of our economic crisis at once," he said.

The U.S. leader called the initial steps introduced to deal with the economic downturn "a good start", but "just a start," and cautioned that "Millions of Americans are still without jobs and homes, and more will be lost before this recession is over."

He urged patience, and with the U.S. economy shrinking by 6.1% in the first quarter of 2009 said it would take time to turn the situation round.

Obama said that in addition to the economy, the country still faces threats "from terrorism to nuclear proliferation to pandemic flu."

The U.S. Center for Disease Control and Prevention said Wednesday that one person had died and 91 people in the U.S. had been confirmed with swine flu. The virus, which started in Mexico, has killed at least eight people worldwide.

Obama called the public health situation "serious" and said the country would do whatever it takes to deal with the crisis adding: "Because this is a new strain, we have to be cautious."