Employees remove stalks from avocados in the Global Fruit Packing Company in Uruapan, in Michoacan state, Mexico, on Jan. 31. (Carlos Jasso/Reuters)

Since coming into office 90 days ago, President Trump has been slow to make progress on one major campaign pledge: renegotiating the North American Free Trade Agreement.

The delay, trade experts say, is partly because the administration has not been able to get confirmed the man who would lead those negotiations. Although Congressional Democrats have tried and failed to stall many of Trump's nominees, they appear to be succeeding in delaying the confirmation of Robert Lighthizer, the administration’s nominee for U.S. trade representative.

The Trump administration came into office with bold plans for trade agreements, including reworking NAFTA, which allows the United States, Canada and Mexico to export and import goods to each other tax free. The pact was a favored target of Trump’s on the campaign trail, where he called it “the worst trade deal maybe ever signed anywhere” and promised to begin renegotiating it on Day One.

But accomplishing these goals is proving difficult without a trade representative, who typically takes charge of international negotiations and serves as an important go-between for the administration and Congress on trade. Speaking from the Oval Office on Thursday, Trump once again called NAFTA a "disaster" and said the administration would be "reporting back sometime over the next two weeks as to NAFTA and what we're going to do about it."

Chad Bown, a trade expert at the Peterson Institute for International Economics, says he believes the Trump administration is hesitant to launch formal NAFTA negotiations until Lighthizer is confirmed.

“Negotiating a trade deal requires detail-oriented, legal expertise. So while Commerce Secretary Ross may lead the administration's strategic efforts, ultimately Mr. Lighthizer and his office are required to cross the t's and dot the i's,” Bown said. “The lawyers are there to make sure the United States doesn't inadvertently sign up to something that it doesn't want.”

Lighthizer may have the most bipartisan support of any top-level Trump official, due to his decades-long career of defending U.S. workers, including representing the U.S. steel industry in disputes abroad and crafting penalties against unfair foreign trade practices as deputy trade representative under President Ronald Reagan.

Yet Senate Democrats have succeeded in holding up his appointment by tying it to a waiver that Lighthizer may need before he can take the office — a strategy that has proved more successful than their attempts to filibuster or vote down Trump's other cabinet-level picks. The White House did not respond to requests for comment.

Senate Democrats say Lighthizer requires a waiver before being confirmed, since his career contained stints working for organizations with ties to foreign governments. A 1995 law prohibits the trade representative from having represented foreign countries in trade negotiations with the United States.

Lighthizer represented the Sugar and Alcohol Institute of Brazil, part of the Brazilian commerce ministry at the time, in its negotiations with the United States in 1985-1986. In the 1990s, he worked with a Chinese electronics group that was part of the government — ties he did not disclose on his original disclosure statement to the Senate Finance Committee.

Senate Republicans have disagreed with the assertion that Lighthizer requires a waiver, but they appear to be going along with it. The waiver could be incorporated in a continuing resolution, which will need to be approved by April 28 to continue funding the government.

“I have stated publicly that I'm willing to work with ranking member Wyden and others on the committee who believe a waiver is necessary,” Sen. Orrin G. Hatch (R-Utah), who heads the finance committee, said during Lighthizer’s confirmation hearing in March. “But I'll be honest, at this point, it appears that my colleagues' assistance on the waiver at the committee level has more to do with their demands for an unrelated ransom, than any concern about the applicability of the statute.”

Democrats have tied their support to the waiver to another piece of legislation, a bill to protect pensions and health-care benefits for thousands of retired coal miners who would lose benefits at the end of April. Senate Majority leader Mitch McConnell (R-Ky.) has proposed his own version of the legislation.

The Democrats say the delay in Lighthizer's confirmation is his and the administration’s fault, since Lighthizer failed to initially disclose that he represented the governments of China and Brazil in trade matters.

“Trump can blame everyone but himself, but the fact is poor vetting and disclosure by the administration was responsible for much of the delay in moving forward with Mr. Lighthizer’s nomination,” said Keith Chu, a spokesman for Sen. Ron Wyden (D-Ore.).

Aaron Fobes, press secretary for Hatch, said the paperwork has been in order for more than two months. He added that the delay may be hurting Americans whose jobs are tied to trade. "By continuing to delay the [U.S. trade representative] confirmation, members of Congress will continue to lack the central administration official needed to hear trade priorities and concerns, further failing their constituencies back home who depend on trade for their economic livelihoods," he said.

Gregory Husisian, partner and litigation attorney with Foley & Lardner, said the waiver issue is probably “just part of a general philosophy of making things difficult for President Trump. ... The waiver is a way to put things off and make the administration seem bumbling, in my view,” he said.

Trade experts agree that the delay in Lighthizer's nomination is bogging down progress on the administration’s trade agenda -- but they point out that many on Capitol Hill may be fine with that.

Trump's plan to renegotiate NAFTA has been a controversial one, especially for the agricultural industry, which exports massively to Mexico and Canada. In Lighthizer's March nomination hearing, senators of both parties emphasized that their constituents do not want to see the administration’s attempts to renegotiate the deal disrupt access to these lucrative markets.

Speaking in Wisconsin on Tuesday, President Trump expressed frustration over the Trade Promotion Authority, a law that gives the president broad powers to negotiate trade deals but also requires him to consult closely with Congress. Bruce Hirsh, a former assistant U.S. trade representative for Japan, Korea and the Asia Pacific, said the president's apparent exasperation may suggest that it's not just Lighthizer's absence that's slowing the administration down, but also that Congress wants more clarity on what Trump's plan is.

I suspect lots of folks are covertly happy to see NAFTA renegotiation drag out for reasons they can blame on somebody else,” said Charles Roh, a former deputy chief negotiator of NAFTA.

See also:

Trump administration launches national security investigation into steel imports

Trump has singled out Mexico. But some say NAFTA’s real challenge is to the north

Trump rails against trade deficit, but economists say there’s no easy way for him to make it go away