Sen. Dianne Feinstein (D-CA) led a group of 12 Democrat leaders in the Senate in writing an open letter to President Donald Trump on Monday urging him to keep the U.S. in the Iran deal.

President Trump tweeted that he would announce his decision on the deal, also known as the Joint Comprehensive Plan of Action (JCPOA), on Tuesday afternoon.

In anticipation of that announcement, Feinstein and eleven other ranking members — senior members of the opposition on Senate committees — sent a letter to the president arguing that he should not back out of the deal.

The text of the letter reads, in part:

If the United States unilaterally withdraws from the JCPOA, Iran could either remain in the agreement and seek to isolate the United States from our closest partners, or resume its nuclear activities. Either scenario would be detrimental to our national security interests. If Iran continues to abide by the agreement following a unilateral U.S. withdrawal, the only effective way the United States could regenerate sufficient economic leverage over Tehran would be to sanction the very same nations that helped us negotiate the JCPOA in the first place, namely persons and businesses from the United Kingdom, France, Germany, Japan, South Korea, Turkey, Taiwan, and India, among others. Under that scenario, it is impossible to imagine the U.S. could rebuild the previous international sanctions coalition that was so effective in getting Iran to the negotiating table. On the other hand, if Iran chooses to resume its unconstrained nuclear activities in the wake of a unilateral U.S. withdrawal, the United States could face a second nuclear crisis at the same time that your administration is seeking a peaceful resolution with North Korea. U.S. credibility in those denuclearization discussions would be severely undermined if North Korea concludes that U.S. leaders are willing to unilaterally abrogate such nuclear agreements without cause. … Instead of effectively withdrawing from the JCPOA by refusing to utilize critical waivers of U.S. sanctions against Iran and its purchasers of oil by May 12th, we urge you to work with our partners and allies to address Iran’s other malign activities while preserving and building upon with our allies the strict nuclear limitations of the JCPOA.

The Iran deal was never ratified by the Senate, and Democrats filibustered an effort to allow an up-or-down vote on the agreement under the terms of the Iran Nuclear Agreement Review Act in 2015.

Not one of the 12 Democrats who signed the letter to President Trump on Monday voted to allow the Senate to vote on the Iran deal in 2015. All joined the party’s filibuster to stop the Senate from reviewing the deal.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.