Several Democratic presidential candidates are advocating  for re-entering the Joint Comprehensive Plan of Action (JCPOA):
Re-entry into the nuclear deal with Iran is fast becoming a litmus test for Democrats hoping to challenge President Donald Trump in 2020.
No fewer than five declared candidates have told Al-Monitor over the past few weeks that they would rejoin the deal without preconditions [bold mine-DL] should they win the presidency — as long as Iran continues to live up to its end of the 2015 pact. These include well-known lawmakers such as Sens. Bernie Sanders, I-Vt. and Elizabeth Warren, D-Mass., who both voted for the deal in 2015, along with Sen. Kamala Harris, D-Calif., who was elected in 2016.
Rejoining the nuclear deal is the right thing for the U.S. to do, and it is encouraging that some of the most prominent Democratic candidates for president are willing to take that position. There have been suggestions  that the U.S. should place conditions on its reentry into the agreement, but that ignores that the U.S. is the only party to the deal that has violated it. It is very good news that these candidates understand that and don’t want to jeopardize the agreement with more unreasonable demands. U.S. reentry into the JCPOA without conditions  is the bare minimum that the U.S. can do to get Iran interested in future talks on any issue, and it is clearly in our own interest to keep a successful nonproliferation agreement from falling apart. If one of these candidates goes on to win in 2020, the first thing that the next administration needs to do is to lift the sanctions that Trump reimposed last year. The Sanders campaign has made it clear that the senator understands that and explicitly supports the return of sanctions relief:
And a Sanders aide said that “as president, Sen. Sanders would rejoin the JCPOA and would also be prepared to talk to Iran on a range of other issues, which is what Trump should’ve done instead of simply walking away. Rejoining the JCPOA would mean meeting the United States’ commitments under the agreement, and that includes sanctions relief.”
Fulfilling U.S. commitments as part of the original agreement is the very least that our government can do after breaching those commitments for years. As a matter of policy, taking the U.S. back into the JCPOA is the correct decision, and it is also the smart political move to draw a clear and significant contrast between the Democratic field and the incumbent president. Trump will run on his record of setting fire to diplomatic agreements, and his opponents are preparing to stand by those agreements, including the nuclear deal with Iran. These Democratic candidates are issuing an important challenge to Trump on foreign policy very early on in the campaign, and they are going to make Iran policy one of the main issues that sets them apart.
Not all of the Democratic candidates have been willing to go this far yet. New Jersey Sen. Cory Booker bizarrely says, “My concern right now, my focus, is the denuclearization of Iran.” That statement sounds equal parts ignorant and hard-line, since it suggests that Booker thinks that eliminating Iran’s nuclear program in its entirety is possible. Many of the other declared candidates have not publicly committed to rejoining the nuclear deal, but it is hard to see how they can hope to be credible critics of Trump on foreign policy if they don’t.