UPDATE: While Murphy initially said his tuition-free plan would cost as much as $400 million, a Murphy spokesman later clarified that the most it would cost would be $200 million.

TRENTON -- Democratic nominee for governor Phil Murphy on Monday formally announced a plan to offer tuition-free community college to all New Jerseyans.

"We simply do not have the workforce that we need," said Murphy, standing on the sidewalk of the Mercer County Community College and flanked by U.S. Sen. Cory Booker, D-N.J. "We can and we must open the doors of opportunity, wide, for all residents."

Four states, including New York, already offer community college free to graduating high school students.

This fall, New York also began offering free tuition to all state colleges and univeristies for first-time college students whose families earn less than $100,000, provided they live and work in-state for the same number of years they receive the award. Those New York residents who depart earlier see their awards convert to a 10 year, interest-free student loan.

Murphy's plan only covers associate's degrees, not baccalaureate's, but it would offer education free of charge to any New Jerseyan, whether they are just leaving high school or looking for a new career. It would not include a means test to qualify.

He said the plan could cost as much as $200 million to fund, and "while you can't get there overnight" but was likely to be phased in after the first two years of a Murphy administration.

A spokesman for Murphy, Derek Roseman, noted that Tennessee, a state with a population roughtly two-thirds that of New Jersey's, has managed to offer free community college to any adult at a cost of $34 million to the state, thanks largely to federal funding and the state lottery.

"This won't be as costly as many critics might have you believe," Murphy said.

A former U.S. ambassador to Germany, Murphy said he'd gotten a front-row seat to some of the world's best technical education. There, German students who wish to become tradesmen receive advanced technical or vocational schooling paired with a two-year course of apprenticeship and study.

Such German vocational schools are usually financed and supervised by the federal government in conjunction with industrial groups, like chambers of commerce, and trade unions -- something Murphy and Booker say they want to replicate in New Jersey.

"Not everyone will need an associates or bachelor's degree," said Murphy. "For many residents, a focused and purposeful training program will prepare them for good paying work."

Booker, for his part, told NJ Advance Media that he was developing federal legislation aimed at funding "apprenticeship training for people sort of at mid-points in their career" including workers who'd seen their jobs evaporate due to cheaper, overseas competition.

"There's a lot of talks going on about trying to do something big in this area, so when you about it as a sort of 'G.I. Bill,' you're using the right language," said Booker.

"We think that we're at such a disruptive point of our economy where many people are losing jobs. By the way, it's not Mexicans; it's microchips. We have to really radically differentiate our economy...We have to start shifting toward major skills training, major apprenticeship programs for our country."

Meanwhile, Ricky Diaz, a spokesman for Republican nominee Lt. Gov. Kim Guadagno, blasted Murphy's plan.

"Insinuating that it is 'free' is a slap in the face to the hardworking taxpayers in New Jersey," Diaz said. "There is no such thing as a free lunch, and all of the 'free' stuff Phil Murphy is promising - government-run healthcare, free college - will have to be paid for by New Jersey taxpayers, who will have to work harder and longer to pay for all of the higher taxes Phil Murphy has promised to increase on everyone."

Claude Brodesser-Akner may be reached at cbrodesser@njadvancemedia.com. Follow him on Twitter @ClaudeBrodesser. Find NJ.com Politics on Facebook.