President Obama signed into law the most significant tax bill in nearly a decade Friday, a day after overcoming liberal resistance in Congress to continue for two more years tax breaks enacted under president George W. Bush and to provide a fresh federal boost for the tepid economic recovery.

In remarks before signing the bill, Obama called it "a substantial victory for middle-class families across the country." He added: "They're the ones hardest hit by the recession we've endured. They're the ones who need relief right now."

Obama described the bill as "a package of tax relief that will protect the middle class, that will grow our economy and will create jobs for the American people."

The package, brokered by Obama and Republican leaders in the wake of the November elections, angered many Democrats, who have long argued that the Bush tax cuts were skewed to benefit the wealthy. But their last-minute campaign to scale back the bill's benefits for taxpayers at the highest income levels failed, and the House passed the measure 277 to 148 Thursday night, with 112 Democrats and 36 Republicans voting "no."

Friday's signing ceremony at the Eisenhower Executive Office Building next to the White House was attended by the Senate Republican leader, Mitch McConnell (Ky.), and the No. 2 Senate Democrat, Richard J. Durbin (Ill.). But notably absent were the top Democratic leaders of the House and Senate.

The $858 billion package prevents taxes from rising on New Year's Day for virtually every American household. The measure also will guarantee unemployed workers in hard-hit states up to 99 weeks of jobless benefits through the end of next year. And it will create major new incentives for business and consumer spending in 2011, including a two-percentage-point reduction in the Social Security payroll tax that would let workers keep as much as $2,136.

At the signing ceremony, Obama said passage of the law was propelled "by the fact that tax rates for every American were poised to automatically increase on January 1st." If that had happened, "the average middle-class family would have had to pay an extra $3,000 in taxes next year," he said. "That wouldn't have just been a blow to them; it would have been a blow to our economy, just as we're climbing out of a devastating recession."

Obama declared: "I refused to let that happen. And because we acted, it's not going to. In fact, not only will middle-class Americans avoid a tax increase, but tens of millions of Americans will start the new year off right by opening their first paycheck to see that it's actually larger than the one they get right now."

He said he would not have signed the bill if it did not include "other extensions of relief that were also set to expire." Among other provisions, he cited the extensions of unemployment benefits and tuition tax credits, as well as new tax incentives for businesses.

Obama acknowledged that "there are some elements of this legislation that I don't like," and some that congressional Republicans and Democrats don't like. "That's the nature of compromise, yielding on something each of us cares about to move forward on what all of us care about," he said. "And right now, what all of us care about is growing the American economy and creating jobs for the American people."

Asserting that the package would do just that, Obama said: "It's a good deal for the American people. This is progress. And that's what they sent us here to achieve. "

Earlier, the incoming speaker of the House, Rep. John A. Boehner (R-Ohio), called the bill "a good first step" but emphasized the GOP view that major spending cuts are needed. "If we want to . . . begin creating jobs, we need to end the job-killing spending binges" by the federal government and "provide more certainty to business," he told reporters Friday on Capitol Hill.