Obama is trying to reassure congressional Democrats on the Iran nuclear deal

In an Aug. 19 letter to Rep. Jerrold Nadler (D-N.Y.), President Obama noted pointedly that the deal to curb Iran's nuclear program doesn't prevent the U.S. from acting unilaterally if Iran tries to cheat. "Should Iran seek to dash toward a nuclear weapon, all of the options available to the United States — including the military option — will remain available through the life of the deal and beyond," the president wrote.

Though the letter is addressed to Nadler, The New York Times says it is "also aimed at other Democrats with concerns about the deal." Obama needs the support of Democrats to sustain an expected veto if the GOP Congress rejects the deal. So far, only two Senate Democrats — Chuck Schumer (N.Y.) and Robert Menedez (N.J.) — and 12 House Democrats have said they will vote against the accord.

Among the new things Obama explicitly laid out in the letter were a pledge to create a White House office dedicated to enacting and monitoring the Iran deal, confirmation that the U.S. could re-impose sanctions piece-by-piece if Iran failed to live up to the deal, assurance that he would use the multinational body overseeing the agreement to keep Iran from getting nuclear-related technology, and a promise to "enhance the already intensive joint efforts" with Israel in the Middle East — including new missile defense funding and tunnel-detecting infrastructure.