Workers will be limited in tapping their 401(k) retirement plans for loans under legislation two senators plan to introduce today that's designed to counter the erosion of retirement assets.

"During these difficult economic times, we are increasingly seeing 401(k) funds being treated as rainy-day funds," Senator Herb Kohl, a Wisconsin Democrat, said in a statement obtained by Bloomberg News. "A 401(k) savings account should not be used as a piggy bank for revolving loans."

Kohl, 76, who's chairman of the Senate Special Committee on Aging, plans to introduce the "SEAL 401(k) Savings Act" with Senator Mike Enzi, 67, a Wyoming Republican. The bill would reduce the number of loans workers may take from a 401(k) and give participants more time to repay after losing a job. It will allow savers to contribute to their plan after taking a hardship withdrawal and ban debit cards linked to the accounts, according to Joe Bonfiglio, a spokesman for Kohl's aging committee.