Republican lawmakers are underwhelmed by the substance of President Trump’s opening moves on Iran, and are pledging to pursue congressional sanctions to force him to put more heat on Tehran.

“I want a lot more to happen – a lot more to happen,” Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) said.

Corker was one of several Republicans who cheered the Trump administration’s decision last week to put National Security Adviser Gen. Michael Flynn put Iran “on notice.” Corker credited the Trump administration for at least acting “quickly, instead of waiting and dilly-dallying around” after the announcement.

Other senators pointed out that Trump’s sanctions weren’t much different than the ballistic missile sanctions Obama imposed on Tehran, despite the president’s criticism of his predecessor as being “weak and ineffective” on Iran.

“I appreciate what the president did, but they’re just sort of what Obama did. Clearly it didn’t work in the past,” Sen. Lindsey Graham (R-S.C.) said. “I promise you, the executive sanctions that we’re doing today is not going to deter Iran.”

On Friday, the Trump administration announced it would impose sanctions on 25 individuals and entities involved with Iran’s ballistic missile program, after Tehran launched the latest in a series of ballistic missile tests last week. Lawmakers in both parties have objected to the tests as violating at least the spirit of the Iran nuclear deal, if not an accompanying U.N. Security Council resolution that says Iran is “called upon not to undertake any activity related to ballistic missiles.”

GOP leaders did praise Trump for the move, noting, as Senate Majority Whip John Cornyn (R-Texas) did, that “it’s a good start.”

Yet lawmakers want a more across-the-board approach that targets Tehran with mandatory sanctions aimed at not only its missile program but also for cyber threats, espionage, and the activities of the country’s Revolutionary Guard Corps. The Trump administration is reportedly mulling designating the IRGC as a terrorist organization.

Last year, Corker filed an Iran sanctions bill along with Sens. Marco Rubio (R-Fla.), Bob Menendez (D-N.J.) and Joe Manchin (D-W.Va.) to address those topics. He intends to revive it – at least as a model – for expanding sanctions against Iran this year.

Corker is also talking to the administration about ways to “unilaterally” extend some of the prohibitions under the Iran nuclear deal, “to really change the effects of what was negotiated,” he said.

Part of the discussions with the administration focus on exploring options to keep Iran from ever getting to the point where it would technically be able to create a nuclear bomb – something former President Barack Obama said could be possible in 13 to 15 years.

“There are multiple stages that we could go through that really get this agreement in a totally different place, from our standpoint,” Corker said, adding that he was “talking with [the Trump administration] a little bit about what makes sense for us to attempt to do together.”

Those talks appear to be exclusively among Republicans.

Democrats have warned Republicans against effectively trying to force a renegotiation of the terms of the Iran nuclear deal, and are highly unlikely to vote for any measure that throws it into jeopardy.

They have not been privy to the discussions taking place between leading GOP senators and the Trump administration about next steps to take on Iran. In fact, according to Senate Foreign Relations Committee ranking member Ben Cardin (D-Md.), they haven’t heard from the administration on Iran at all.

“It’s been a one-way communication: I don’t think I’ve heard back on anything I’ve communicated,” Cardin said, adding that he was “not aware of any member of Congress that was engaged in such discussions with the White House.”

Cardin said he had no objections to the substance of sanctions Trump announced against Iran last week, he was troubled by the fact that Democrats were not warned beforehand.

“My concern is not what he did, it’s how he did it,” Cardin said, explaining Trump “should have been in consultation” with members of Congress, the departments, and U.S. allies before unveiling new punitive measures.

The discrepancy is notable considering how frequently Cardin and Corker coordinated on Iran sanctions in the past, both in the runup to the nuclear deal and in its aftermath.

The two began to part ways last year, when a months-long negotiation process to tackle more expansive Iran sanctions broke down – leaving Corker to introduce his measure with Rubio, Menendez and Manchin, and Cardin to join other Democrats in angling for an undiluted extension of existing Iran sanctions. The Democrats’ preferred version of Iran sanctions eventually passed the Senate.

Democrats are unlikely to support any effort that would dismantle the Iran nuclear deal, even though four from their ranks – Cardin, Menendez, Manchin, and Senate Minority Leader Charles E. Schumer (D-N.Y.) voted against the Iran deal.