President Barack Obama's aides warned Americans on Sunday not to expect instant miracles from the $787 billion economic stimulus bill he will sign this week, but said it would help eventually.

Obama is due to sign the bill passed last week by Congress in Denver on Tuesday. It was the first major legislative victory of his young presidency, which could rise or fall with its success or failure.

There will be signs of activity very quickly, David Axelrod, the White House senior adviser, said on Fox News Sunday. But it's going to take time for that to show up in the statistics. The president has said it's likely to get worse before it gets better.

White House spokesman Robert Gibbs used similar language on CBS' Face the Nation.

I don't think there's any doubt that we've seen this economy has gotten worse just in the last few months. The acceleration in job loss probably means that this economy is going to get worse before it gets better, he said.

Obama himself said last week that if he failed to heal the economy, he would be out of a job by 2012, when he faces re-election.

The White House hopes the package will save or create 3.5 million jobs. Mark Zandi, chief economist at Moody's Economy.com, said on Fox News Sunday that was likely too optimistic.

By my estimate, it will add 2 to 2.5 million jobs, more than would be the case without stimulus, by the end of 2010. That translates into a lower unemployment rate of about a point to a point and a half, he said.

Only three Republican senators supported the bill and no Republicans in the House of Representatives backed it. They kept up their criticism on the Sunday television talk shows.

This bill was not bipartisan. It is incredibly expensive. It has hundreds of billions of dollars in projects which will not yield in jobs, said John McCain, whom Obama defeated in last year's presidential election, said on CNN's State of the Union.

Gibbs said Obama's team had crafted a stimulus bill to produce jobs as quickly as possible in an economy that lost 3.6 million in the past year.

BALANCED APPROACH

The urgency to get something done was very important, he said. What we have here is a very balanced approach that's going to put people to work.

Obama faces a new potential flashpoint next week when two Detroit automakers, General Motors Corp and Chrysler LLC, must reach agreements with the United Auto Workers labor union to restructure themselves.

Talks between GM and the union broke down on Saturday. Chrysler's negotiations with the UAW are also deadlocked.

Axelrod made it clear the White House would not intervene in the situation until after Tuesday.

Obviously, this is a difficult situation and everyone's going to have to continue to work toward a solution. We're going to wait and see what the automakers have to say on Tuesday and we'll go from there, he said.

On a third front, Obama plans to issue a plan to tackle the housing crisis next week, hoping to stem a flood of home foreclosures that has weakened the banking system and frozen credit markets while continuing to depress house prices.

(Editing by Patricia Zengerle)

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