In the latest and most comprehensive effort to win over lawmakers hesitant to back the Iran nuclear deal, President Obama penned a letter this week to congressional Democrats promising the U.S. will keep all options on the table should Iran violate the agreement.

"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," Obama wrote in the letter dated Aug. 19 and obtained by The New York Times.

Addressed to New York Democrat Rep. Jerrold Nadler, but also meant for other Democrats concerned about the deal, Obama reasserts that the deal stuck between Iran and the P5+1 world powers is a good one that will prevent Tehran from developing a nuclear weapon. The agreement curbs Iran's nuclear program in exchange for international sanctions relief.

Obama laid out a number of steps the U.S. will take, including enhancing security cooperation with Israel and Gulf allies and the continued enforcement of sanctions placed on Iran for its support of terrorism and human rights violations, the Times said.

Obama also said the State Department will be establishing a separate office to implement the nuclear accord.

"In addition, Representative Adam Schiff of California, the ranking Democrat on the House Intelligence Committee, said that the letter expanded assurances that sanctions lifted under the nuclear accord could be reimposed piece by piece, not all at once, to keep Iran in compliance," wrote the Times. "Mr. Obama's pledge to use the multinational commission policing the accord to block Iranian procurement of nuclear-related technology is new, as is the president's explicit pledge 'to enhance the already intensive joint efforts' of the United States and Israel in the region, said Mr. Schiff, a supporter of the deal"

The Republican-led Congress has until Sept. 17 to vote on a resolution of disapproval for the agreement, which is expected to pass, leaving Obama unable to lift U.S. sanctions on Iran. Obama has promised to veto any resolution of disapproval, and he has been lobbying Democrats to secure the 67 votes needed to sustain his veto.

"The President and senior members of his team have been in regular consultation with Members of Congress, including Representative Nadler, to ensure they have the information they need to judge the deal on its merits," a White House official said, reported Reuters. "The letter reaffirms the Administration's stalwart commitment to our regional allies, chiefly Israel."

The Times reported Friday that Nadler, who represents a district with many Jews, will support the deal. Nadler had questions regarding the strength of restrictions placed on Iran's nuclear program and how the U.S. will counteract Tehran's support of terrorist groups that threaten Israel, but he said Friday that the president's letter answered his questions.

"A number of us raised these concerns with the administration, and directly with the president, in the hope that certain assurances could be made, and I am gratified that the president's response satisfies a number of these concerns," he said in a statement, according to The Hill.

Earlier this month, Sen. Charles Schumer, another influential Democrat from New York, said he will not support the agreement. Sen. Robert Menendez of New Jersey also recently came out against it, as HNGN reported.