U.S. President Barack Obama keeps the focus squarely on the troubled American economy this week as he signs a massive stimulus package into law, and announces steps to help the housing market.

The almost $790-billion stimulus bill is the biggest economic package ever passed by Congress.

The president's top White House advisor, David Axelrod, says its size befits the problem.  He predicts the stimulus package will have an impact quickly.  But he warns it will be difficult to undue all the economic damage that has already been done.

"As you know, the package will help fund infrastructure programs and other programs that are ready to go around the country," he said. "But it is going to take time for that to show up in the statistics."

Speaking on the Fox News Sunday television program, Axelrod said it is necessary to act aggressively to keep the situation from getting much worse.

"We are in the worst recession since World War II," he added.  "And it took us a long time to get into this mess. It is going to take us a while to get out of it."

The president is going outside Washington to sign the stimulus bill into law.

Instead of a ceremony at the White House attended by politicians and dignitaries, Mr. Obama will put pen to paper on Tuesday in Denver, Colorado - the same city where he accepted the Democratic Party's presidential nomination in August.

Press Secretary Robert Gibbs says the choice of Denver shows how important it is for the president to hear from people outside the nation's capital.

"He wants to get out of Washington and show people all across America the benefits of what is inside this economic recovery and reinvestment plan," said Gibbs.

Gibbs told the CBS program Face the Nation that the president will travel from Denver to Phoenix, Arizona where he will unveil his proposal to deal with the home mortgage foreclosure crisis.

It is the mess in the housing market that is widely regarded as the trigger behind the current economic recession.  Banks put up millions of dollars in risky mortgage loans to home buyers who later found they could not keep up with the payments.  Families lost their homes, and banks tightened credit, making it more difficult for others to borrow money.

Gibbs said the president will continue to reach out to Republicans as the administration puts together the details of the housing proposal.  This, despite the fact the stimulus package got no Republican votes in the House of Representatives and only three in the Senate.

"He is going to continue to reach out to Republicans and he is hopeful Republicans will start to reach back," said Gibbs.

But Republicans are still angry over the stimulus package, which they say was rammed through Congress by the White House and the Democratic majority in the legislature.

Senator Lindsey Graham, a South Carolina Republican, told ABC's This Week the stimulus bill failed the bipartisanship test.

"There is nothing about this process that has been bipartisan.  This is not change you can believe in," said Graham.

But Graham said he still hopes the two sides can come together when the president's housing proposal hits Capitol Hill.