U.S. President Donald Trump is attacking General Motors, the country’s biggest automaker, for costing 5,400 factory workers their jobs when it closed a manufacturing plant where it built a compact model car that Americans were increasingly not interested in buying.

Trump said on Twitter he talked with Mary Barra, GM’s chief executive, on Sunday, telling her he was “not happy” that the automaker closed the manufacturing plant in the industrial heartland of the country in Lordstown, Ohio, where GM manufactured the Chevrolet Cruze, a smaller car the company says is still popular overseas but not in the U.S.

He said he was miffed that the Lordstown plant was closed earlier this month “when everything else in our Country is BOOMING. I asked her to sell it or do something quickly.”

The plant closure was an indication that prosperity is uneven geographically across the U.S., the world’s largest economy.

But with Trump facing several investigations surrounding his 2016 presidential campaign and his actions during the first 26 months of his presidency, he is counting on the country’s mostly robust economy as a key talking point to voters that he should be re-elected to another four-year term in the November 2020 election.

He wrote on Twitter that he is not happy about the closure.

Trump on Monday tweeted that GM, the fourth biggest automaker in the world, and the UAW are opening negotiations on a new contract in September and October.

But he demanded, “Why wait, start them now! I want jobs to stay in the U.S.A. and want Lordstown (Ohio), in one of the best economies in our history, opened or sold to a company who will open it up fast!”

About 4,500 workers at the Lordstown plant lost their jobs over the last two years as sales of the Cruze model declined sharply, along with another 900 at nearby car parts suppliers.

A small portion of the laid-off workers have found jobs at other GM plants far from the Ohio plant that was closed.

Some of the unemployed workers have sought retraining for new jobs, but often found their years of work on a manufacturing assembly line do not readily translate into the ability to handle jobs where newer technology-related skills are needed.

Annual sales of the Cruze in North America peaked at 273,000 in 2014, but last year totaled just 142,000, as Americans are buying fewer passenger cars and instead opting to purchase bigger sport utility vehicles or pickup trucks.

Even as it closed the Lordstown plant, GM is continuing to manufacture the Cruze model in Mexico, Argentina and China, where the wages it pays workers are substantially less than the wages it was paying the Lordstown employees.

GM says Cruze sales in foreign countries have remained stable, fallen less sharply than in the U.S.. or even increased, as is the case in South America.