WHEN DENNIS CARDOZA launched his reelection campaign in 2010 to represent California’s 18th District in the House of Representatives for a fifth term, he said he was “fired up” to be running again. Somewhere along the line, Mr. Cardoza, a centrist Democrat from the San Joaquin Valley, lost that fire. Last October, he announced that he would not run again, lamenting the partisan atmosphere in Washington.

His voting attendance record in the House this year was abysmal. According to the Web site Govtrack.us, he missed 26.5 percent of roll call votes in the first three months of this year and wasn’t around for 38.1 percent in the second quarter. Then Mr. Cardoza threw in the towel altogether. On Aug. 14, he quit Congress, effective the next day. “In light of the fact that nothing is going to happen for the rest of the year,” and facing “increasing parenting challenges,” Mr. Cardoza told the Sacramento Bee, “this seemed like the right time to make this move.”

Lest anyone worry about Mr. Cardoza’s future, he seems not to have been idle. According to Politico, he notified the House ethics committee on July 30 that he was negotiating a job with the lobbying firm of Manatt, Phelps & Phillips LLP, and he recused himself from any official matter that could cause a conflict. On Aug. 4, Mr. Cardoza left for a five-day, taxpayer-paid trip to Europe. On Aug. 16, the day after his resignation from Congress, Mr. Cardoza was named a managing director in Manatt’s federal government affairs and public policy practice, based in Washington.

Even if he was fed up with Congress, why couldn’t Mr. Cardoza remain in office until the end of his term? Why the rush through the revolving door? His statement that he needed more time for parenting must be viewed with sympathy. But it is also true that, by resigning early, Mr. Cardoza got a jump on the one-year “cooling-off” period under the law, during which he cannot lobby his former colleagues. Now he can begin to lobby them next August, rather than waiting until January 2014.

Those extra few months of lobbying may be lucrative for Mr. Cardoza, but what about the voters he left behind? There won’t be a special election to succeed him. If there are roll call votes in the coming months, the 18th District of California might as well be on the moon. Mr. Cardoza seems to have landed on his feet, but he left his voters in the lurch.

Congress should amend the law: If you resign early, the one-year prohibition on lobbying should begin a year from the end of your term, not from the day you decide to abandon your constituents for a cushy lobbying job.