The so-called payroll to population employment rate, also called the P2P rate, measures how many people 18 years old or older are working 30 hours or more per week for one employer.
Gallup said the P2P rate in January was 43.7 percent, down from 44.4 percent in December, and virtually unchanged from January 2012, when it was 43.6 percent.
Gallup said its underemployment rate, which combines the unemployment rate with the percentage of workers working part time but looking for full time work, was 17.4 percent in January -- a slight gain from December, when the underemployment rate was 17.1 percent, but a drop from January 2012, when the rate was 18.7 percent.
The percentage of workers with part-time jobs who wanted full-time work was 9.6 percent in January, up from 9.4 percent in December, but down from 10.1 percent in January 2012.
Gallup said gains in the unemployment rate were dependent on self-employment options and on workers finding part-time jobs.
"While these undoubtedly qualify as jobs and are better than unemployment, Gallup's global employment research has shown that these aren't the types of jobs that are linked to (a) higher gross domestic product," Gallup said.
Gallup said its economic confidence index was at its highest reading in the past five years. With the stock market in a recent rally and Congress pushing ahead on budget issues, there is reason to be optimistic the labor market would improve in 2013, Gallup said.
Gallup said its figures were based on more than 27,000 interviews conducted Jan. 2-29. The margin of error is 1 percentage point.