U.S. President Donald Trump criticized General Motors Co. for shrinking its U.S. manufacturing presence, which has reduced the company’s unionized workforce to the smallest among Detroit’s automakers.

“General Motors, which was once the Giant of Detroit, is now one of the smallest auto manufacturers there,” Trump tweeted Friday, a day after Bloomberg News reported GM employed fewer United Auto Workers-represented employees than Ford Motor Co. or Fiat Chrysler Automobiles NV. The president called for GM to “start moving back to America again.”

GM has about 46,000 UAW workers, about 2,000 fewer than it had in 2009, when the company emerged from a bankruptcy reorganization backed by the U.S. government. The automaker trails Ford by about 9,000 union-represented employees and Fiat Chrysler Automobiles NV by roughly 1,200, according to headcounts provided by the companies.

A GM spokesman didn’t immediately comment on Trump’s tweet.

By calling attention to GM’s decline, Trump has added to the pressure the company will be under at the bargaining table later this year. GM, Ford and Fiat Chrysler are negotiating new four-year labor contracts with the UAW, and union leaders have vowed a take-no-prisoners approach to talks amid an embarrassing corruption scandal.

In his tweet, Trump claimed GM had moved major plants to China before he became president, which is incorrect. While GM has added several factories in China over the last decade, the company has expanded its manufacturing base there almost entirely to produce for that market.

GM’s expansion in Mexico has been a greater culprit behind its stagnant U.S. manufacturing headcount. The UAW has attacked the company’s decision to build the new Chevrolet Blazer in Mexico starting last year, which helped GM overtake Japan’s Nissan Motor Co. as Mexico’s top carmaker.

This article was provided by Bloomberg News.