While the White House hails data showing an improved U.S. labor market, Republican presidential contenders continue to blast President Barack Obama's economic performance.

It is the central political issue of 2012: the U.S. economy, which suffered the worst recession of the post-World War II era in 2007 and 2008, and has endured an anemic recovery since. But the economic landscape may be changing. U.S. unemployment has fallen for four consecutive months, down from 9 percent in September to 8.3 percent in January.

While Wall Street rallied Friday on the latest jobs report, President Obama highlighted the good news. "In January, American businesses added another 257,000 jobs. The unemployment rate came down, because more people found work. And altogether, we have added 3.7-million jobs over the last 23 months," he said.

The response from Republicans vying to challenge the president in the November election? Too little too late to alter what they see as Mr. Obama's failed economic stewardship. Addressing supporters after his caucus victory Saturday in Nevada, former Massachusetts governor Mitt Romney pointed out the Obama administration initially aimed to keep the unemployment rate at 8 percent or less.

"This week he has been trying to take a bow for 8.3-percent unemployment. Not so fast, Mr. President. This is the 36th straight month with unemployment above the red line your own administration drew," he said.

Former House Speaker Newt Gingrich had a similar line of attack on NBC's "Meet The Press" program. "Unemployment has dropped. Well, it has dropped. You know why? Because over 4 percent of the people who would be unemployed have quit looking for work. If we had the same participation rate we had a couple years ago, we would be at 12- or 13-percent unemployment," he said.

For President Obama, a fine line to walk: trumpeting good news while acknowledging the need for further improvement. "There are still far too many Americans who need a job or need a job that pays better than the one they have now. But the economy is growing stronger. The recovery is speeding up. And we have got to do everything in our power to keep it going," he said.

Polling firms report modest improvements in President Obama's approval ratings that coincide with recent positive economic data.