The nation’s largest union umbrella organization is now supporting the new North American trade pact based on recent revisions to labor terms that not all unions are immediately ready to declare as a win for workers.

AFL-CIO President Richard Trumka, whose endorsement was considered critical to getting Democrats on board with the U.S.-Mexico-Canada Agreement, praised the reworked pact Dec. 10 for improving worker protections. Trumka cited newly negotiated rules and enforcement language as key to getting him and Democratic leaders to end their holdout on the deal to replace the North American Free Trade Agreement. It’s the first trade deal the AFL-CIO has endorsed since 2001.

But at least one prominent AFL-CIO member, the International Association of Machinists and Aerospace Workers, quickly came out in opposition to the pact, while other unions were noncommittal. That could be a sign of further cracks in labor support for the agreement, which is considered a must have for the Trump administration and for moderate Democrats facing close reelection battles next year.