Some of Nafta’s original architects defended the accord to U.S. lawmakers Tuesday as Senate Republicans downplayed U.S. President Donald Trump’s threats to quit the pact.

In a hearing Tuesday at the U.S. Senate Committee on Foreign Relations, Chairman Bob Corker said his sense is that “modernization is where the administration is heading,” while Senator James Risch, a fellow Republican, said Congress is united in viewing Nafta as a deal that should be improved but not killed.

“This is a genie that doesn’t go back in the bottle, so it has to be done, and you’re not hearing from members of Congress—anyone that I know of—saying we ought to be out of Nafta. Can we do better? I think we can do better,” he said, adding that Trump himself campaigned on doing better in Nafta. “We can, we should and I really think that eventually we will.”

The hearing came one day after the end of the sixth round of Nafta talks, which ended with progress but a U.S. demand to speed things up. Trump is set to address his trade agenda in the State of the Union speech Tuesday night. The senators weren’t unanimous in their general praise of Nafta and its potential to be improved—Democrat Jeff Merkley of Oregon said the deal is in part to blame for stagnant American wages and is a “more complicated picture and puzzle than the very rosy depictions I was hearing here.”

Still, Corker said he didn’t think there was much chance the deal would die. Speaking afterward in an interview, he said, “I know there is the possibility of our withdrawing from Nafta. I don’t think that’s going to happen.”

Brian Mulroney, the Canadian prime minister who signed the original Nafta; Jaime Serra Puche, who led the original Nafta negotiation for Mexico; and, Earl Anthony Wayne, who served as U.S. ambassador to Mexico under Barack Obama, as all testified. Each called for Nafta modernization, rather than its death.

“Protectionist impulses can easily become a convenient handmaiden,” Mulroney said. “If it ain’t broke, don’t fix it. We can modernize Nafta, we can improve it, we can do all kinds of things, but we shouldn’t throw it away.”