WASHINGTON - March 21, 2010 - The United States has thrown trillions of dollars at the slumping housing market and it still looks wobbly.

The government seized the two biggest mortgage finance companies and offered as much as $8,000 in tax breaks to entice home buyers, while the Federal Reserve has bought more than $1 trillion in mortgage-related assets as a way to drive down borrowing costs.

Yet a series of reports this week will likely show home sales remained weak in February. Although bad weather is partly to blame - snowstorms struck the densely populated East Coast last month - it does not fully explain the poor demand.

If Tuesday's report shows a drop in existing home sales for February, as economists polled by Reuters expect, it would mark the third consecutive month of declines and push the sales pace back to levels seen last summer, when mortgage rates spiked.

Wednesday's report on new home sales, which represents only a sliver of the housing market, is expected to show a slight increase. However, the new home segment remains moribund. Builder confidence is near an all-time low and both housing starts and permits fell in February.

Housing was at the heart of the global Depression, and plays a crucial role in the U.S. economy. During the boom years, rising home values left Amerikans feeling flush, and they were able to tap home equity to boost spending. The bust has taken a $10 trillion bite out of household wealth, and spending has suffered.

As poorly as the housing market has performed so far this year, some economists think it may soon get worse. The tax credit, which was expanded and extended late last year, expires in April, the Fed is wrapping up its mortgage asset purchases by the end of this month, and millions of homeowners are behind on payments, leaving them vulnerable to foreclosure, which tends to drive down prices of neighboring homes.

As for the Fed's efforts, between cutting interest rates to near zero and buying up mortgage-related assets, the central bank has successfully pushed mortgage rates down. The average rate on a 30-year mortgage has hovered near 5% in recent weeks, but that has not been enough to spark much activity.

What happens to rates when the Fed wraps up its asset-buying program at the end of this month is a big question mark. Fed officials expect minimal market reaction, but the central bank has never embarked on such an ambitious buying spree and cannot be certain what will happen when it ends.

Economists at IHS Global Insight offered other reasons for concern about the housing market's path.

"Economic conditions remain dire, with unemployment likely to remain stubbornly near 10% for some time," the firm wrote in a quarterly housing market report on Friday. "In addition, the federal tax credit for first-time buyers played a significant and temporary role in bolstering the market."

The national housing market was 8.9% undervalued at the end of 2009, and not a single metropolitan area was considered "extremely overvalued." Contrast that with 2005, the height of the housing bubble, when 52 metro areas were judged to be extremely overvalued.

Since that peak, 10 metro areas have seen home prices fall by more than half, and 31 have recorded drops of more than 40%. That is a big reason why household wealth has dropped by $10 trillion since 2007.

No matter how hard Washington tries to speed up the process, housing market repair is likely to take a while.