Just as lawmakers and the Obama administration are working to revive a still-troubled labor market, a new risk is rising on the economic horizon. Long-term interest rates are quietly heading higher.

The common perception is that the Federal Reserve is keeping rates low. In fact, Fed chairman Ben Bernanke indicated in February that rates for households and businesses would remain stable. The Fed only controls certain interest rates, though. For the most part, rates are set by trading in the financial markets.

In the financial markets, long-term interest rates critical to businesses and investors are on the rise. The yield on the 30-year bond is now 4.70 percent, or 3.76 percentage points higher than the yield on the two-year note. The difference between long- and short-term rates, known as the yield curve, reached 3.85 percentage points on February 17, the highest level in 30 years.

The rising yield curve means that investors are increasingly worried about the risk of inflation a few years into the future. Those concerns have been stoked by the high level of public debt. Rising rates also reflect the huge load of debt on the market, which the Obama administration has issued to finance its spending.

The U.S., which had a surplus as recently as 2001, is expected to run a deficit of $1.6 trillion this year, accounting for 10.6 percent of the economy. The government is auctioning off an additional $13 billion in debt today.

Rising rates are a drag on the economy, making it more difficult for businesses and households to finance spending and investment. That's not necessarily a bad thing. Sometimes the economy is growing too quickly and needs to cool off so that inflation doesn't become a problem. Yet that is hardly the case now.

The latest figures on unemployment show a U.S. economy still struggling to emerge from the worst downturn since the Great Depression, a situation that is sparking at least some action in Congress.

On Thursday, the Labor Department said state unemployment benefit claims fell less than expected, by 6,000, to 462,000 from 468,000. Analysts had expected claims to drop to 460,000, according to Reuters. The unemployment rate remains 9.7 percent, although there is hope that the economy will generate hundreds of thousands of jobs in March.

The U.S. is exporting its economic weakness too. The Commerce Department said Thursday that the trade gap fell 6.6 percent, to $378.3 billion, mostly because of falling demand for oil. U.S. exports had declined too, a sign of lower economic activity all around.

With jobless claims stubbornly high and employers reluctant to boost their payrolls, the U.S. Senate Wednesday passed a $149 billion package of tax cuts and jobless aid. About 40 percent of the unemployed have been out of work for six months and are running out of benefits. The bill that the Senate passed on Wednesday would pay for the extension of existing wage and health care benefits through the end of this year. It also extends $25 billion in tax breaks for employers that hire workers.

The bill, passed by a 62-36 vote, now goes to the U.S. House for approval. In the House, it may grow into a larger package. There, Democrats have pushed for a bigger bill to help lower the 9.7 percent national unemployment rate. The U.S has lost 8.4 million jobs since the recession began in late 2007.

President Obama seemed happy with the Senate’s action. "I am grateful to senators in both parties who took one more step forward today in getting our nation back on a solid economic footing," he said in a statement.

Lawmakers and President Obama can only exert so much control over the economy, however. As the government spends more money to stimulate the economy, interest rates are bound to rise. And over time, those higher rates may slow the economy, just as the administration and Congress want to speed it up.

Portfolio.com News Editor Kent Bernhard Jr. contributed.