DETROIT — The government will end its popular “cash for clunkers” program on Monday, more than two months early, because it is already running out of money.

Patrick and Lynn Wentland shopped with Cassidy, right, and Alexandra in Colorado Springs.

The sudden halt means new-car showrooms are likely to be flooded by last-minute shoppers over the weekend. Dealers have until 8 p.m. Eastern time on Monday to submit the 13-page application to be reimbursed for the rebates they are giving out under the program.

Although the program has brought on a welcome surge in demand for cars after months of dismal sales, some dealers will be glad to put it behind them because it has been plagued by confusion and processing delays.

General Motors...