The government's wildly successful Cash for Clunkers trade-in program ends in a matter of hours, but if you've waited until the last day to take advantage of the opportunity, you may have a hard time finding a dealer who will take your clunker. Thousands of dealerships pulled out of the program early.

The Washington Post reports, "Many dealerships stopped accepting clunker trade-ins on Friday or Saturday because they were worried about getting their paperwork submitted before the program ends at 8 p.m. Monday." Dealerships bear considerable risk with each Clunkers transaction. The Post notes, "The program allows consumers to trade in gas guzzlers for a voucher worth up to $4,500 toward the purchase of a new vehicle. Dealers must essentially front the money until they are reimbursed by the government, and many have yet to receive those reimbursements."

CNN Money notes, "The Virginia Automobile Dealers Association reported late last week that about 25% of its member dealerships had already dropped out of the program because of uncertainty over getting paid for their deals. The Virginia auto dealers' group reports that dealers have been reimbursed for only about 3% of all the deals that have been done in that state."

The nation's largest chain of auto dealerships shut ended its Cash for Clunkers participation on Friday. The AP reports, "AutoNation Inc...hit the brakes on the popular Cash for Clunkers program three days early because it wants to make sure it can submit the paperwork on thousands of sales to the government before a Monday evening deadline." The company, which operates 220 dealerships representing more than a dozen automotive brands spread across 15 southeastern states, "Has sold 11,000 cars under the rebate program as of Thursday night, and estimates the government owes it $45 million."

Some dealers, CNN notes, have "described the submission process as challenging, with frequent problems and rejections." Dealers submit the transactions through a government website, which has frequently been slow, overwhelmed with demand. Some dealerships learned to tap into the system late at night, when demand was lower, in order to process transactions more quickly. But that presented its own problems, as paying employees overtime ate away at the profit the program had generated.

Tammy Darvish, vice president of Maryland's Darcars automotive group, told CBS News "We have about $5.5 million out there. I'm sure the government will make good on it sooner or later. But not knowing when and how long that money will be hanging out there - it's just not a very comfortable way."

If you're interested in the Cash for Clunkers program, check out our Cash for Clunkers page.  If you're ready to buy, contact local dealers. For the latest news on the program, check out Cash for Clunkers news.