Virginia Lt. Gov. Ralph Northam unveiled a plan Thursday to make community colleges­ and workforce training free in certain high-demand fields such as health care, cybersecurity and skilled construction trades.

Northam, who is seeking the Democratic nomination for governor, would also require students who benefit from the program to commit to a year of public service.

Northam’s rival in the June 13 primary, former congressman Tom Perriello, has variously advocated for “debt-free” and “tuition-free” community college, apprenticeships and vocational training.

Northam and Perriello are hitting on the theme of college affordability as they compete for the progressive voters energized by Sen. Bernie Sanders (I-Vt.), who called for making public universities free as he ran unsuccessfully for the 2016 Democratic presidential nomination.

At a news conference held at state Democratic Party headquarters Thursday, Northam rolled out a detailed plan for preparing Virginians for what he called “new-collar” jobs: high-demand, well-paying positions that require an associate degree or some type of workforce certification but not a four-year diploma. He said that Virginia has a shortage of people trained in those fields, which include clean energy, computer programming and early-childhood education.

“We have Virginians who are eager to learn the skills and we have unfilled, well-paying jobs offered by employers eager to find qualified workers,” he said. “We need to start matching the skills employers need for new-collar jobs, with the skills being taught to our workers.”

[Virginia governor’s race: Democrats Northam, Perriello on hot-button issues]

Under Northam’s plan, students pursuing a training credential or associate degree in the targeted fields could rely on the state to pay their “last-dollar” tuition and fees — meaning, after they have exhausted all other aid. In return, the students would have to commit to one year of public service, such as working in an economically depressed region of Virginia, in local or state government or for a nonprofit organization.

Northam said the program would require an initial state investment of $37 million — one that he said would yield $75 million in higher income tax revenue over five years.

Perriello has not gone into that level of detail. On his campaign website, hepromises to make “vocational training, apprenticeships or community college available debt-free for a minimum of two years.” In an appearance in Roanoke on Friday, he said tuition should be free for two years of community college.