WASHINGTON (JTA) — Sen. Ben Cardin, D-Md., said Friday that he would vote to reject the Iran nuclear deal in Congress and proposed legislation to maintain tight controls on Iran should it cheat on the deal.

Cardin, who was closely watched as the top Democrat on the Senate Foreign Relations Committee and as one of the Jewish leaders in the Senate, said in an Op-Ed in the Washington Post that his decision was a “close call.”

While the nuclear deal contains “significant achievements,” including tough restrictions on Iran’s nuclear program for up to 15 years and the ability to resume sanctions should Iran cheat, Cardin said, the deal also “legitimizes Iran’s nuclear program.”

The deal “would provide this legal path to a country that remains a rogue state and has violated its international nonproliferation obligations for years,” he said. “It would provide Iran with international endorsement of an industrial-scale nuclear program. Worse, Iran would be economically strengthened by frighteningly quick relief from sanctions and international economic engagement.”

His decision brings to three the number of Democrats who will vote against the deal in the Senate. The others are Sens. Charles Schumer, D-NY, and Robert Menendez, D-NJ. So far, 38 Democrats in the Senate say they will support the bill, more than the 34 necessary to prevent an override of President Barack Obama’s pledged veto of any bill killing the deal. The latest Democrat to announce backing was Sen. Michael Bennet, D-Colo., on Friday.

Congress has until Sept. 17 to consider the deal. All but one of the 54 Republicans have said they will reject he deal; only Susan Collins of Maine is undecided. That leaves five Democrats who are also undecided.

Even with approval of his deal assured, the Democratic leadership and the White House are pressing undecideds hard to back the deal in order to get to the 41 votes in the body necessary to filibuster a vote to disapprove the deal.

Cardin, a scion of a leading Maryland Jewish family who is also close to the president, came under intense pressure from both sides in recent weeks.

The legislation he proposes in his Op-Ed appears to be a compromise on post-deal legislation favored by Republicans that effectively would reimpose sanctions stripped away by the deal. Cardin’s proposal, by contrast, would reimpose sanctions only in the event that there is “evidence that Iran has committed an act of terrorism against the United States or substantially increased its terrorist activities.”