After advancing out of the Senate Armed Services Committee on Wednesday, the nomination of Colin Kahl, President Joe Biden’s choice for undersecretary of defense for policy, will go to a full Senate vote in the coming weeks. 

A spokesperson for Sen. Bob Menendez (D-NJ), chairman of the Senate Foreign Relations committee, told Jewish Insider on Thursday that the New Jersey senator is undecided on whether he will back Kahl’s nomination, which will likely require support from every Democrat.

Menendez, a vocal opponent of the 2015 Iran deal, has been at odds with Kahl, one of the negotiators of the deal, in the past over Iran policy. Wednesday’s committee vote to advance Kahl’s nomination was tied 13-13, with all Democrats voting in favor and all Republicans voting against Kahl. 

Senate Armed Services Chair Jack Reed (D-RI) predicted Wednesday that Kahl could face a 50-50 tied vote on the Senate floor, with Vice President Kamala Harris serving as a tie-breaker.

In Kahl’s confirmation hearing earlier this month, Republicans criticized him for his controversial Twitter history, in which he frequently attacked legislators — including Menendez. 

In 2013, Kahl characterized a Menendez-sponsored bill that would have imposed additional sanctions on Iran as “a diplomatic train wreck.” In 2014, he referred to Menendez as part of “the Iraq war crowd supporting” Iran sanctions legislation, linking to a blog post which called the bill “AIPAC’s Iran bill” and the sponsors “neocons.”

Kahl also predicted that the new sanctions Menendez supported would lead Iran to escalate its nuclear activity and said the bill “undermines diplo[macy], makes war more likely.”

On a panel in 2017, Kahl criticized another Menendez-sponsored sanctions bill as having the potential to “undermine the [2015] deal” and possibly provoke the Iranian Revolutionary Guard Corps to attack American forces. Overall, however, Kahl said it was “a good faith effort” from Congress.

Sen. Krysten Sinema (D-AZ), another centrist Democrat who is sometimes regarded as a swing vote in the evenly divided Senate, did not respond to a question from JI about how she plans to vote on Kahl’s nomination.

The Senate is in recess for two weeks starting Monday and a date for a vote on Kahl’s confirmation has not been set.