The following editorial appeared recently in The Orange County (Calif.) Register.

New York Democratic Sen. Chuck Schumer over the past three weeks has wrestled with whether to support the so-called Joint Comprehensive Plan of Action, the nuclear pact to which the United States and five other world powers agreed with the Islamic Republic of Iran.

President Barack Obama had counted on Schumer’s support for what would be the signature foreign policy achievement of his two terms. But Schumer announced instead that he was breaking ranks with the president.

“Every several years or so,” said Schumer, “a legislator is called upon to cast a momentous vote in which the stakes are high.” Experience has taught him, he said, to “make a decision solely based on the merits” and “without regard to pressure, politics or party.”

The New York senator decided against the deal, he said, “not because I believe war is a viable or desirable option, nor to challenge the path of diplomacy. It is because I believe Iran will not change, and under this agreement it will be able to achieve its dual goals of eliminating sanctions while ultimately retaining its nuclear and non-nuclear power.”

Meanwhile, in the House, a growing number of Democrats have said they intend to vote against Obama’s nuclear deal; the latest being New York Rep. Eliot Engel, the ranking Democrat on the House Foreign Affairs Committee, who announced his opposition the same day as Schumer.

Engel said he struggled with his decision “because this is a Democratic administration and a president I’ve worked with.”

He asked administration officials to address certain troubling questions he had about the JCPA. However, he said, “The answers I’ve received simply don’t convince me that this deal will keep a nuclear weapon out of Iran’s hands, and may, in fact, strengthen Iran’s position as a destabilizing and destructive influence across the Middle East.”

That respected Democrats have parted ways with Obama on the Iraq nuclear deal puts the fritters to the president’s repeated insinuation that opposition to the deal on Capitol Hill is mostly a matter of Republican partisanship.

Indeed, we believe that Congress faces one of those momentous votes that come along once ever several years, as Schumer suggested. And, if lawmakers reject the Joint Comprehensive Plan of Action, we are confident that most will do so based on the merits rather than petty political considerations.