The sluggish state of the economic recovery has been at the heart of Republican attacks on President Obama, as he begins to make his case for reelection. Over the past several months, though unemployment began to decline, the White House has maintained a cautious optimism, noting each time that although economic signs were improving, much more work remained to be done.

More recently, however, Obama sounded more confident, even confrontational, in his economic message, signified by his State of the Union declaration that “America is back.” On Friday, he seized on the Labor Department’s January jobs report as proof that the nation’s economic recovery “is speeding up,”with the economy creating 243,000 new jobs and unemployment falling from 8.5 percent to 8.3 percent.

He also took the offensive with Congress, demanding that lawmakers extend the payroll tax cut and long-term unemployment insurance, both of which expire at the end of the month.

“Do it without drama, without delay, without linking it to ideological side issues,” Obama said at an Arlington firehouse, where he proposed creating a Veterans Job Corps to put 20,000 veterans to work over the next five years. “Now is not the time for self-inflicted wounds. I want to send a clear message to Congress: Don’t slow down the economic recovery we’re on. Do not muck it up. Keep it moving in the right direction.”

The job numbers helped bolster the Obama campaign’s narrative that the economy has shown a consistent trend upward since the president took office. On its Web site, the campaign posted a chart that illustrated 23 consecutive months of private-sector job growth and encouraged supporters to e-mail it to friends “to make sure people know the good news about President Obama’s record on jobs.”

The chart included a summary of White House initiatives since Obama took office, including the Recovery Act, which provided a $787 billion stimulus; a bailout loan to the auto industry; and the payroll tax cut. (The chart did not mention the public sector has continued to shed jobs, forestalling a more robust recovery.)

A campaign official, speaking on condition of anonymity to discuss strategy, said the chart had already become one of the campaign’s most popular social media items, having been e-mailed and posted on Facebook and Twitter hundreds of thousands of times by Friday afternoon.

“The trend since this president took office is what’s most significant,” the campaign official said. “It’s the story over time as the president has taken action to address the historic economic challenges he faced when he came into office.”

White House officials, and Obama himself, have acknowledged that the recovery is still fragile, and the employment numbers are likely to fluctuate in the coming months, with uncertainties ranging from the European debt crisis to Iran’s nuclear weapons program posing threats to the U.S. economy.

But Friday’s report was more encouraging for the White House than other reports from recent months that suggested jobs growth was due in part to temporary, seasonal jobs during the holiday season and to large numbers of unemployed people giving up on their job searches altogether.

Friday’s numbers showed large gains in manufacturing, which Obama has made a centerpiece of his State of the Union agenda to create a more equitable economy that boosts the middle class. Political analysts said the positive growth could provide Obama leverage in his negotiations with Congress on the payroll tax cut and other economic initiatives.

“It puts Congress and Republicans in the position of going against what in many cases are very logical proposals they have backed in the past to create jobs,” said Peter Fenn, a Democratic strategist. “Then you get into this thing that is very dangerous for Republicans of them needing to do everything they can to beat Obama even if it suppresses jobs numbers, which is a very dangerous road to go down.”