MILWAUKEE — Gov. Scott Walker said Tuesday he's yet to visit a prison in Wisconsin and he doesn't plan to if he's re-elected because "there's no value" in him doing so.

He made the comments during a news conference to criticize Democratic gubernatorial candidates who say they want to reduce the state's prison population by releasing some inmates early. A week before Democrats choose the candidate to challenge Walker in November, the Republican governor said "there cannot be a starker contrast" between himself and his potential opponents.

"This is about as clear cut as it gets," Walker said. "If you believe that violent offenders should be let out early, then one of these candidates is probably your candidate."

Walker said that although he hasn't visited a state prison, he has spoken to offenders who participated in employment training programs. He said inmate job training is a better alternative to reforming the correctional system than releasing offenders early.

The Democratic gubernatorial candidates are: Tony Evers, who is state schools superintendent; Mahlon Mitchell, a firefighter and president of the state firefighter union; Matt Flynn, an attorney and U.S. Navy veteran; Josh Pade, an attorney making his first run for office; former state Rep. Kelda Roys; Mike McCabe, a political activist; Paul Soglin, Madison's mayor; and state Sen. Kathleen Vinehout.

Democrats quickly lashed out, with Mitchell saying Walker's refusal to visit any of the state's prisons, which cost about $1 billion to operate annually, is proof the governor "is unfit to lead and will be replaced in November."

Evers noted incredulously in a statement: "How can the governor — who oversees a billion dollars a year in Corrections funding — refuse to visit a corrections facility?" He said the state needs to be "smarter on crime" and invest in drug courts and rehabilitation programs.

Roys called Walker's comments "cheap scare tactics and fear-mongering."

Flynn said Walker's refusal to visit a prison amounted to "criminal negligence" and showed that Walker "wants to turn a blind eye to problems."

Vinehout, meanwhile, noted that Minnesota's prison population is less than half that of Wisconsin, even though the states have about the same number of residents.

"Our people are no more violent than they are. Minnesotans are no less safe than we are," Vinehout said.

Wisconsin's prison population stood at 23,519 inmates as of the end of 2017, according to state Department of Corrections report. Sixty-seven percent of inmates had committed a violent offense.

Democrats' plans to reduce the prison population include releasing ill and aging inmates, legalizing marijuana, and releasing inmates early for good behavior.