Small U.S. businesses still face a very tough economy and are experiencing more challenges than larger businesses after the recession, Treasury Secretary Timothy Geithner said Tuesday.

"Small businesses are more concentrated in construction and retail, industries that were at the epicenter of the crisis and have not returned to pre-recession levels," Geithner said in prepared remarks to the Senate Small Business Committee.

Citing a lack of demand and poor sales as the biggest hurdles for small businesses, Geithner tried to convince lawmakers that the Obama administration's $447 billion jobs program would help struggling firms hire, invest and expand.

The administration's jobs proposal would extend the employee payroll tax holiday.

Geithner urged Congress to support specific provisions in the proposal. Senate Republicans have already blocked the overall bill, forcing the administration and Senate Democrats to consider pushing parts of the bill through Congress.