AMONG THE world’s democratic politicians, the lamest of lame ducks may be Mexico’s outgoing president. Felipe Calderón watched the election of his successor, Enrique Peña Nieto, in July, but Mr. Calderón’s term does not end until Dec. 1.

His government hasn’t shut down: The president is using new constitutional powers to force Mexico’s Congress to vote on a major labor market reform. On Thursday, security forces captured a drug-trafficking kingpin — one of three to be arrested last month.

But Mr. Calderón’s most important function during the interregnum might be to talk frankly about the biggest challenges Mexico faces, both at home and in its relations with the United States. That the president did last week during an address to the United Nations General Assembly and in several public appearances in Washington. The straight talk offers a useful guide to the problems that Mr. Peña Nieto and the winner of the Nov. 6 U.S. election ought to tackle, singly and together.

Inside Mexico, Mr. Calderón said in an appearance at the Mexican cultural center in Washington, “the most important challenge” for Mr. Peña Nieto will be structural reform of the energy industry. Mexico’s weakening oil production is controlled by a constitutionally established state monopoly, Pemex; Mr. Calderón’s attempt to allow foreign investment was watered down by populists in Congress. “I went for a touchdown and got a first-and-10,” Mr. Calderón said. “Now it’s time to do the touchdown.”

Not surprisingly, Mr. Calderón’s agenda for U.S.-Mexican relations begins with comprehensive U.S. immigration reform — even if, as he pointed out, net Mexican migration to the United States fell to zero in 2010-11. There is also work to be done along the border, including new bridges and crossing points.

But Mr. Calderón’s toughest talk concerned the fateful war Mexico is fighting against narcotics traffickers, which has cost more than 50,000 lives in the past six years. At home, he said, the task is to “make Mexico a rule-of-law state” where the police and judiciary are effective and incorruptible. Yet that is unlikely to happen as long as cash and assault weapons continue to flow from the United States: Mr. Calderón says that 80 percent of the 150,000 weapons confiscated by Mexican authorities were purchased in U.S. gun shops.

Mr. Calderón says that a renewal of the U.S. ban on assault weapons is essential — and he is hinting that a new approach to managing drug consumption by Americans is needed, too. If demand for drugs cannot be reduced, he said, then the flow of money to the drug cartels must be interdicted; and if this cannot be done, “it’s time to explore different alternatives when it comes to reducing consumption.” While the president did not spell out what he had in mind, he mentioned “regulatory and market alternatives” — by which he likely means some form of legalization.

This is a message many in Washington will reject. But Mr. Calderón is raising issues that lawmakers in both countries have ducked for too long. If his parting message prompts a serious debate, his lame-duck time will have been worthwhile.