Former Vice President Joe Biden urged displaced coal miners to take up coding and computer programming on Monday during a campaign swing through New Hampshire.

Biden, who recently claimed that blue-collar job losses should not stand in the way of a greener economy, made the comment while discussing his plans for expanding “jobs of the future” if elected in 2020. The former vice president, in particular, suggested retraining programs were the key for workers in industries hardest hit by globalization and increased environmental regulations, especially those in the coal mines of Appalachia.

“Anybody who can go down 3,000 feet in a mine can sure as hell learn to program as well,” Biden told an audience in Derry, New Hampshire. “Anybody who can throw coal into a furnace can learn how to program, for God’s sake!”

The former vice president’s comments come only weeks after he pledged at the sixth Democrat primary debate to “sacrifice” economic growth and potentially “displace thousands or hundreds of thousands of blue-collar workers” in the interests of a “greener economy.”

“The answer is yes because the opportunity for those workers to transition to high paying jobs is real,” Biden told the audience.

Regardless of the former vice president’s claim, job retraining and other transitionary programs for displaced workers have mostly failed to live up to their promise. Retraining programs are often a poor fit for blue-collar workers, an overwhelming majority of whom tend to be older and lack a college education, in terms of skill set and technological literacy. Even more troubling is that the jobs eligible for retraining often are either in short supply in areas hardest hit by globalization and automation, or pay significantly less than those initially displaced.

For instance, the average pay a coal miner can expect to make, under a contract negotiated by the United Mine Workers of America union, “comes out to at least $61,650 a year, and closer to $85,000 a year with overtime.” This does not include healthcare, pension, and other benefits usually offered by such jobs. Meanwhile, the jobs available after workforce retraining generally tend to be lower-paid hourly wage positions.

Biden, himself, should be aware of such circumstances. A study measuring the impact of retraining programs, both existing ones and those began under the Obama administration, found that while they helped enrollees find work faster, there was little proof such programs led individuals to jobs of equal or higher wage to those they lost.

Despite such evidence, Biden has not only continued touting the idea of job retraining, but has also promised to ban energy sources such as coal, fracking, and other fossil fuels if elected president—to the detriment of millions of workers in those fields.