Thirteen Senators Who Could Make History

"These include security hawks such as Virginia's Mark Warner and Tim Kaine, or Michigan's Gary Peters, as well as others who have been skeptical about Iran's intentions from the get-go, and several senators with significant Jewish constituencies, including Florida's Ben Nelson, Cory Booker of New Jersey and New York's Chuck Schumer, who is currently viewed as the biggest prize on the Senate floor."

Guttman acknowledges that the security hawks in the Democratic caucus, all of whom have strong emotional ties to Israel, are dead set against the deal, falling in line behind Israel's Prime Minister Benjamin Netanyahu.

This leaves 13 undecided Democratic senators who must choose to support the Democratic president. If any one of these senators goes to the Israeli side, the deal collapses.

Guttman looks at the 13 undecided senators now under the spotlight.

"Advocates believe that Schumer's decision, thanks to his senior position in the Democratic Party (he is slated to take over as majority leader next year) and to his standing in the Jewish community, could play a significant role in influencing other undecided Democrats."

The 13, including Schumer, will be watched carefully in the weeks leading to the final vote on the deal. All of them are essential to sustain a final Obama veto of the Congress' attempt to scuttle the deal.

Below are the 13 U.S. Democratic senators identified by Forward, as undecided on how they will vote on the Iran diplomatic deal. Some of them have not commented on the deal, others are studying it.

Outside these 13, other Democratic senators could yet emerge to support President Obama and the deal. That, however, does not appear likely.

The Democratic undecided senators below are identified by their state. The Forward offers their current position on the vote. All are needed to sustain Obama. Voters in their states still have time to communicate to Senate offices locally or in Washington.