U.S. senators opposed to the nuclear deal signed between Iran and the West are hard at work on new sanctions on the Islamic Republic and are not buying the president’s warnings against new sanctions, reports The Washington Post.

According to the report, published Sunday, a bipartisan group of senior senators is spending the remaining week of the Thanksgiving recess forging an agreement on a new sanctions that the senators hope to pass before breaking again at the end of December.

Soon after the deal was signed on November 23, a group of 15 senators had already declared they would push for more sanctions on Iran.

The move is more than likely to upset President Barack Obama, whose administration has been pushing the senators to hold off on passing any new sanctions on Iran. Obama believes the legislation could scuttle the interim nuclear agreement reached with Iran on November 23 and derail upcoming negotiations on a permanent deal.

“If you want to hold our feet to the fire on the final deal, fine, do that,” a senior administration official told The Washington Post.

“If people have concerns about elements of a final agreement, come in and tell us. . . . But that is a separate discussion from passing a sanctions bill in the middle of negotiations,” said the official.

The administration contends that new sanctions not only would violate the terms of the interim agreement but also could divide the United States from its international negotiating partners across the table from Iran and give the upper hand to Iranian hard-liners in upcoming talks.

“The purpose of sanctions from the outset was to create a dynamic so that you can get a change in policy from the Iranians,” David Cohen, the Treasury Department’s undersecretary for terrorism and financial intelligence, told the newspaper.

“It’s not sanctions for the sake of having sanctions,” he noted.

According to The Washington Post, the White House has organized a full-court press between now and the Senate’s return December 9 to persuade lawmakers not to act.

Presently, in addition to briefings for anyone who wants one, Obama, Secretary of State John Kerry, national security adviser Susan Rice and other top officials are making personal calls, reported the newspaper.

Kerry sent a video to his former Capitol Hill colleagues explaining the deal, “because some people are putting out some misinformation on it.”

On Friday, the National Security Council distributed to reporters a 25-page compendium of what it called “welcoming” comments about the agreement from lawmakers, foreign policy experts and editorials.

A separate 19 pages listed foreign governments, from Afghanistan and Albania to the United Arab Emirates, that have said anything remotely positive.

Nathan Diament, executive director for public policy at the Union of Orthodox Jewish Congregations of America, told The Washington Post he listened in on three White House conference calls last week — two to pro-Israel groups and one to a broader collection of faith-based groups — during which officials stated their case.

“This is going to make the president’s Hanukkah party very interesting,” said Diament, whose group favors new sanctions. The American Israel Public Affairs Committee (AIPAC) has declared passage of a sanctions bill its top current priority.

Obama has urged Prime Minister Binyamin Netanyahu, who has called the interim agreement a “historic mistake,” to “take a breather” from his criticism and shift attention to the terms of the final deal still under negotiation.

Netanyahu’s top national security advisers are due in Washington this week to express Israel’s concerns and hear the administration’s arguments, according to The Washington Post.

Senate Foreign Relations Committee Chairman Robert Menendez (D-N.J.), one of the leading proponents of new sanctions, said he wonders what all the fuss is about.

“From my perspective, it strengthens the administration’s hand” and positions the United States “for the possibility that [a permanent] agreement cannot ultimately be struck,” Menendez told the newspaper of a new sanctions bill.

“It would make clear to the Iranians if they don’t strike a deal, this is what’s coming,” he added.

“I find it interesting that the Iranians can play good cop, bad cop with ‘hard-liners’ in their country,” said Menendez, while “we can’t.”

Menendez told The Washington Post he favors a measure that would bring further reductions in international purchases of Iranian oil and find new opportunities for sanctions on Iran’s private sector.

While some other proposals include requirements ranging from presidential reports to Congress every 30 days during the interim period to an outright ban on U.S. dealings with any country buying Iran’s oil, Menendez would vote now but delay implementation for six months until it was clear that the long-term negotiations had failed.

Obama recently told lawmakers that Iran would make progress in its ability to build a nuclear weapon if there is no diplomatic deal to halt or roll back its nuclear program.

He has also issued a public warning to Congress, saying that a deal in the works could prevent the “unintended consequences” of war.