A key lawmaker is demanding that more than 100 mortgage companies determine whether foreclosure documents they approved contain errors and reveal their findings.

Sen. Robert Menendez, D.-N.J., says he sent letters to three banks that have halted foreclosures in 23 states after evidence surfaced that their employees or outside lawyers signed documents without reading them. Menendez leads a Senate subcommittee that oversees housing issues.

He wrote to the three major lenders that have halted some foreclosures — JPMorgan Chase, Bank of America and Ally Financial — along with dozens of other companies.

"I want to know how deep this problem goes and what safeguards are now in place to prevent unjustified rubber-stamp foreclosures from happening in the future," Menendez said.