CQ Roll Call took a look at how each of the 11 undecided senators may come out on the Iran nuclear deal and whether the agreement should be filibustered. The assessment is based on the senators’ legislative histories, statements, re-election prospects and constituent concerns.

Sen. Michael Bennet, D-Colo.

Bennet signed on as an early co-sponsor of the Iran Nuclear Agreement Review Act (PL 114-17), which could be interpreted as a sign that he supports Congress making its voice heard on the deal even if he ultimately decides to personally support it and the president’s veto.

He is up for re-election in 2016 in a swing state.

Even though Bennet made some hawkish statements during his tenure as chairman of the Democratic Senatorial Campaign Committee for the 2014 elections, “he is a leaning ‘yes’ in my whip sheet,” said Jamal Abdi, executive director of NIAC Action, a group created by the National Iranian American Council to advocate for the nuclear accord.

Sen. Richard Blumenthal, D-Conn.

Blumenthal was an early co-sponsor of the Iran review act as well as a co-sponsor of the most recent Iran sanctions legislation (S.269) from Sens. Mark S. Kirk, R-Ill., and Robert Menendez, D-N.J.

“I’m counting him as leaning for but I would not take that to the bank,” Abdi said.

Larry Kudlow, a CNBC contributor and a conservative, has threatened to run against Blumenthal next year if he supports the Iran deal.

Sen. Cory Booker, D-N.J.

Booker is seen as somebody who wants to be a progressive leader in the Democratic Party and who has national aspirations, which would make it difficult to go against a nuclear deal that the liberal party base and the current president are ardently backing.

At the same time, Booker hails from a state with a very well-organized, vocal pro-Israel community that has come out strongly against the deal. “Booker’s constituents hate this deal,” said Omri Ceren, senior adviser for The Israel Project, an organization that opposes the terms of the nuclear deal.

New Jersey’s senior senator, Menendez, publicly came out against the deal earlier this summer. He is under indictment on federal corruption charges. “In a context like this, it is difficult to go against the senior senator even if he is someone who may be on his way out,” Ceren said.

Sen. Maria Cantwell, D-Wash.

Cantwell has been focusing during August on the wildfires in her state much more than the Iran deal, so she may not announce a decision on the agreement until next week.

Boeing Co. has major facilities in Washington state and could financially benefit from the Iran deal, since the accord would permit the export of U.S. commercial passenger jets and parts to Iran.

Sen. Benjamin L. Cardin, D-Md.

In remarks at the University of Maryland Wednesday, Cardin criticized the practice of a minority of senators filibustering a measure that had the support of a majority in the Senate.

He also minimized the importance of the cloture vote when compared to any vote to override the president’s veto: “It’s not going [to] make any difference. Because the critical vote is 67, not 60. So, I’m not sure why there’s so much tension in [the] filibuster vote.”

Ceren said it would be difficult for Cardin to support a filibuster given that his name is so publicly attached to the Iran review act, which at its heart is about giving Congress the ability to consider and vote on the Iran deal.

Maryland is home to a sizable Jewish constituency which opposes the Iran deal, but that has not stopped other lawmakers from the state such as its senior senator, Barbara A. Mikulski, from coming out in support of the deal Wednesday morning. Mikulski’s announcement clenched the minimum number of votes required to sustain a presidential veto.

Sen. Susan Collins, R-Maine

Collins, a GOP moderate, is seen as the only hope of getting any Republican support for the deal in the Senate now that Jeff Flake of Arizona has come out against it.

The four-term senator hails from a state that “as a general rule  . . .  is anti-war, pro-peace,” said Joy Drucker, an independent consultant involved in rallying congressional support for the Iran deal.

Angus King, the state’s junior senator and an independent, came out in favor of the agreement and was well received at home for that decision, which may play into Collins’ own political calculus, Drucker said.

Sen. Heidi Heitkamp, D-N.D.

The first-term senator was one of the first Democrats to sign on to the Iran review act when it was introduced by Sen. Bob Corker, R-Tenn. in late February. So it may be hard for her to vote against voting on it.

Heitkamp votes overwhelmingly with the president, but the red-state Democrat has deviated from Obama on a number of top issues, mostly domestic matters like gun control and energy. Her term runs through 2018, so that could give her some space to support the Iran deal, if she is inclined to do so. She may also run for governor in 2016.

Sen. Joe Manchin III, D- W. Va.

“Manchin is a senator who started out on everybody’s whip lists as a likely vote in favor of the deal but after going home [for the August recess] and listening to his constituents and their concerns expressed over multiple town halls, is now broadly thought to be in play,” Oren said.

He has taken hawkish stances on Iran issues in the past, including signing on as an early co-sponsor of the 2015 Kirk-Menendez Iran sanctions bill.

Sen. Gary Peters, D-Mich.

Peters is seen by Abdi as one of the undecided Democrats that is more likely to come out against the Iran deal, though the freshman lawmaker is at present keeping his cards close to his chest.

His predecessor, former Senate Armed Services Committee Chairman Carl Levin and his older brother Rep. Sander M. Levin, both powerful Jewish voices in the state, came out in support of the deal. Still, Drucker said that may not make much difference in swaying Peters. “My sense of Peters is that he is independently minded,” she said.

Sen. Mark Warner, D-Va.

Abdi and other deal advocates have Warner down in their whip count sheets as leaning yes though is by no means certain.

Sen. Ron Wyden, D-Ore.

The Jewish senator is seen by Abdi as another Democrat that could break in favor of deal opponents.

“He is facing a number of dynamics running through [Oregon] that are counter to one another,” Drucker said, noting the state’s active base of Jewish voters that oppose the deal as well as a general constituency of progressive Oregonians that support the agreement.

 Wyden has a record of bucking his liberal constituents, as was evidenced most recently with the critical role he played in getting fast-track trade authority passed in the Senate.

Aisha Chowhdry and John M. Donnelly contributed to this report.