The prospect that the Obama administration may abstain from a vote at the United Nations condemning America is one of the most astonishing pieces of news we’ve read in weeks. The matter on which it might abstain, the Associated Press reports, is the resolution that comes up annually condemning the United States trade embargo of the communistic regime in Cuba. The wire is quoting American officials as saying that the administration is weighing an abstention on the vote, which could come in October. The wire reckons that “merely considering an abstention is unprecedented.”

File this one under “the water’s edge.” Our current politics have long since crossed the beach beyond which the country is traditionally supposed to speak with one voice. The Cuba embargo is different. It is a series of laws. Congress passed them according to constitutional procedures. Presidents signed them. Among them were John Kennedy and William Clinton. One of those laws, the Cuban Democracy Act, contains legislated, bright-line pre-conditions for ending the embargo and moving to normal relations. The Cuban communists have met none of these legislated pre-conditions.

So an abstention in respect of the United Nations annual condemnation of the embargo is special. It would be a case of an America president formally standing apart from his own country. It would a mockery, while on the soil of the United Nations, of the faithful execution clauses of the President’s own constitutional oath. There are those who will say this is par for the course with President Obama, who has already raced ahead of Congress and re-opened our embassy at Havana. The Cuban embargo, though, is clearly a congressional prerogative.

This is because of the Constitution’s commerce clause. It is among the enumerated powers of Congress, set forth in Article 1, Section 8, which says that Congress shall have the power “to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.” This is much clearer than, say, the Jerusalem passport case, where the president asserted authority under the reception clause that grants him the power to receive ambassadors. Here the grant of power to congress is unambiguous. No other branch of government is granted the power to regulate commerce with foreign nations.

We’d like to think that between now and next month, when this vote is scheduled, the administration will come to its constitutional senses. Senator Rubio, one of the foreign policy sages running for the Republican nomination, is quoted by the AP as saying that by abstaining, Mr. Obama would be “putting international popularity ahead of the national security and foreign policy interests of the United States.” The embargo, he said, denies money to a dictatorship that can be used to further oppression. It’s lucky, in any event, that the U.N. won’t be able to enforce the resolution against the U.S., even if Mr. Obama abstains.