WASHINGTON — The country’s poverty rate is falling for the first time since President Bush took office in 2001, while the number of uninsured Americans is rising, data released today by the U.S. Census Bureau show.

The percentage of people living in poverty dropped in 2006 to 12.3%, down from 12.6% a year earlier, marking the first statistically significant decrease since 1999. For the second straight year, the nation’s median household income rose, to $48,200 in an increase of 0.7%, according to the annual census report.

The positive trends in income and poverty were tempered by the rise in the number of Americans without health insurance, which stood at 47 million in 2006. That represents an increase of 2.2 million people from 2005, or 0.5%. The number of uninsured children also increased by 700,000, or 0.8%

Despite the drop in the poverty rate, Democrats seized on the insurance numbers to renew their calls for an expansion of government health care programs and a push toward universal coverage.

“The need for fundamental change in our government is obvious,” a Democratic presidential candidate, John Edwards, said in a statement. “We simply cannot stand by while tens of millions of our fellow citizens go without the necessities of life. We need truly universal health care and a national effort to eliminate poverty.”

Senator Clinton said the report “demonstrates the urgent need to cover every American,” while Senator Obama said that “in the richest nation on Earth, it is a moral outrage that one in ten American families live in poverty and 47 million Americans do not have health care.”