One of Donald Trump’s top advisers split with the Republican presidential nominee on the North American Free Trade Agreement during a debate Thursday in Washington on economic policy.

Trump’s adviser Stephen Moore and Democratic nominee Hillary Clinton’s economic adviser Gene Sperling also presented drastically different visions of how to stimulate economic growth and tackle the deficit and debt, though the discussion was light on specifics. The debate between the advisers was sponsored by the nonpartisan National Association for Business Economics.

Trump has been highly critical of NAFTA, arguing on the campaign trail that he will renegotiate or scrap the three-country pact, which went into effect in 1994. His plan for “fighting for free trade” has been a main plank in his campaign.

When asked to defend Trump, Moore said he wouldn’t. “I don’t fully agree with him on trade. I disagree with him on NAFTA, frankly,” he said.

But Moore, a distinguished visiting fellow at the Project for Economic Growth at the conservative Heritage Foundation, qualified his answer by saying that “there is something to what he says on trade,” referring to voters’ frustration about the lack of economic growth and increased financial stress among working-class Americans. And he threw barbs at Clinton for what he said was flip-flopping on the Trans-Pacific Partnership, a trade pact among 12 nations on the Pacific Rim.

[Trump Castigates Global Trade Pacts, Lawmakers Caught in a Vice]

But Sperling, a former director of the National Economic Council, defended Clinton’s skepticism on the TPP and seized on the moment of division between Trump and his economic adviser.

Sperling said he believes Trump will “go outside the global agreements and do things that … I think many people worry will end up hurting our ability to create jobs through exporting.”

Moore, otherwise in the debate, stressed the need for business tax cuts to serve as a primary means to spur economic growth and increase revenues to the Treasury.

Sperling presented a more comprehensive approach. He said Clinton would make changes to Medicare beyond those imposed by the 2010 health care law, enact an immigration overhaul, increase spending on infrastructure, manufacturing and small business, and deliver tax breaks to middle-class Americans to ease the cost of child care.

Moore spent much of the debate laying out a case against theories that stress spending on economic stimulus, pointing to tepid economic growth as evidence that major stimulus packages following the 2008 housing crisis were ineffective.

He also emphasized that repeal of the health care law would significantly decrease health care costs.

“The most important thing we’re going to do on entitlement reform is repeal Obamacare,” Moore said.

He said that in his view, regarding entitlements more broadly, “I don’t think you have to cut the Social Security benefits if you get growth back up.”

[Not Your Father’s GOP: The Deficit Debate Has Disappeared]

Sperling advocated expanding Social Security, though he qualified his answer by saying that “campaigns have never been the greatest place to try to work out a Social Security solution.”

But he objected to what he called a characterization by many during the presidential campaign that Social Security essentially needs to be reduced in order to be fixed.

“There is nothing that we have in government that is as efficient, as rock-solid, and is as well done as Social Security,” Sperling said, pointing to uncertainty in private pension liabilities and growing concern about older Americans’ retirement security. He conceded that would require revenue increases, which could come in a number of forms including additional “high-income revenues.”