A top Republican on Sunday said it would be a mistake for President Donald Trump to abandon the Iran nuclear deal because it would diminish Washington’s leverage over Tehran.

Rep. Mac Thornberry, R-Texas, chairman of the House Armed Services Committee, told 'Fox News Sunday' that he “would counsel against” Trump scrapping the nuclear deal.

Though he opposed the deal in 2015, when it was signed into law by President Obama, he said now is not the time to walk away from the agreement.

He said he thought it was a bad deal.

“Iran got most of the benefit upfront with relief of sanctions and a plane load of cash that President Obama sent over there. So we've lost a lot of our leverage,” he said. “But the key question is: OK, now we are where we are. What happens next if the U.S. pulls out? Does Iran kick those inspectors out so that we lose what visibility we have there?”

He added that “you need to have a clearer idea about next steps if we are going to pull out, and especially given the larger context of Iran's aggressive activities in the Middle East.”

The comments from Thornberry comes amid the May 12 deadline when the Trump administration will have to decide whether to re-impose sanctions against Iran.

The administration has indicated that it’s in favor of exiting the nuclear agreement as it failed to stop the Islamic Republic’s ballistic missile program and curtail the country’s growing influence in the region.

Trump told the American Israel Public Affairs Committee in 2016 that his “number-one priority is to dismantle the disastrous deal with Iran.”

Thornberry said Trump should instead work with European countries, which are set to re-impose the sanctions, to improve the agreement. “The Europeans are not going to re-impose sanctions so where does that leave us and Iran?” he said.

The sentiment was echoed by French President Emmanuel Macron who said in April during the state visit to the U.S. that he hopes Trump won’t pull out from the agreement.

Last week, Israeli Prime Minister Benjamin Netanyahu made a pitch to scrap the nuclear deal in a presentation revealing new “dramatic” intelligence that claims to show Iran is “brazenly lying” about its nuclear weapons program and hasn’t complied with the deal since 2015.

The new intelligence was reportedly obtained by the Israelis. Netanyahu said the "half a ton" of files were moved to a "highly secret" location in the capital of Iran.

"These files conclusively prove that Iran is brazenly lying when it says it never had a nuclear weapons program," he said.