WASHINGTON – President Barack Obama signed legislation Wednesday to expand publicly funded health insurance for children, marking a historic shift in Washington’s political landscape and providing the White House its biggest victory since Obama took office.

Less than two years ago, former President George W. Bush blocked similar bills by congressional Democrats, labeling the proposed expansion of the State Children’s Health Insurance Program as a step toward government-run health care.

But with Democrats now firmly in control of the White House and Congress, the party’s leaders easily pushed through a $33 billion bill that is expected to provide government subsidized insurance to 4 million mostly low-income children.

That would reduce the number of uninsured children in America by about half over the next 4 1/2 years and boost the number covered by the program to 11 million.

Sen. Patty Murray, D-Wash., said that the bill will make 6,000 children in Washington newly eligible for care.

The measure – funded primarily by boosting the federal tax on cigarettes by 61 cents, to $1 a pack – sailed through the House earlier Wednesday on a largely party-line vote of 290-135. The Senate overwhelmingly approved the bill last week.

The swift passage came in marked contrast to the economic recovery package, which is currently mired in debate on Capitol Hill despite pleas from Obama for congressional action.

The bill was an early benchmark in the planned Democratic campaign to reshape the nation’s health-care system over the next two years.

“The way I see it, providing coverage to 11 million children … is a down payment on my commitment to cover every single American,” Obama said before signing the bill in the East Room of the White House.

The new president also drew on language from an earlier era, when Washington more openly embraced the expansion of the government-funded safety net. “We’re not a nation that leaves struggling families to fend for themselves,” he said.

SCHIP, as the program is called, was created in the late 1990s when President Bill Clinton and a Republican Congress addressed concerns that families who earned too much to qualify for public assistance through Medicaid nonetheless could not afford insurance for their children.

Most of the 7 million children enrolled in SCHIP programs nationwide come from families with incomes less than twice that of the poverty line.