WASHINGTON – Big companies are building up cash and are expected to report strong earnings starting this week. Not so for small businesses that can’t get loans — or hire freely until they do.

The gap helps explain why the economic rebound isn’t stronger and could even stall. Federal Reserve Chairman Ben Bernanke stepped up pressure Monday on banks to break the logjam and lend more to smaller firms, which employ at least half of American workers.

Small-business owners are relying on personal credit cards or raiding retirement accounts to stay afloat, the Fed chairman said.

Bernanke and other regulators have urged banks for months to lend more to smaller companies. Lawmakers have complained that small businesses that want loans are having trouble getting them.

Banks have countered by saying demand remains weak.

The Fed does have authority to create programs to increase lending, such as providing low-cost loans to banks.

But economic conditions would probably have to weaken considerably before the Fed would propose such a move. One such program set up during the 2008 financial crisis was recently closed.

The Fed chief’s latest comments came as legislative efforts to spur small-business lending have languished, and as the recovery has lost momentum.

“Making credit accessible to sound small businesses is crucial to our economic recovery,” Bernanke said. “More must be done.”

Some small business leaders say they would hire more if only they had easier access to loans. One of them is Marilyn Landis of Basic Business Concepts Inc. of Pittsburgh, which compiles financial documents for other small businesses.

Landis says she would like to hire one or two more people for her 10-person firm and wants to expand into New England. Yet even though she says she’s never missed a payment, Landis says her line of credit was cut about 18 months ago.

She relies on credit cards to pay for everything from supplies to payrolls. Without additional credit, she says, “It is impossible to expand, and I can’t hire.”

Nearly one-third of small business borrowers report difficulty arranging credit, the National Federation of Independent Businesses says.