Boston City Councilor Michelle Wu's proposal to introduce a residential parking fee has a high-profile skeptic: Mayor Marty Walsh.

Walsh told Boston Public Radio Friday that he doesn't believe Wu's plan — which she hopes will reduce congestion and traffic-related pollution in the city — is "fair."

"Charging somebody who lives in the city of Boston, who pays taxes in the city of Boston, who owns a home in the city of Boston or rents in the city of Boston," Walsh said, "charging them for a parking sticker to park on their street, I just don't feel is fair."

Walsh's wide-ranging interview with Boston Public Radio also touched on other topics, including the search for a new Boston Public Schools superintendent.

Wu's proposal would levy a $25 fee on a resident's first vehicle, and the price would increase by $25 for each additional vehicle (a parking permit would cost $50 for a resident's second vehicle, and so on.)

Wu said in a statement earlier this week that the proposal will "bring our resident parking permit program into the 21st century, and to align the value of our public streets with a smarter approach to parking management.”

Walsh is hoping that changes to parking meter fees and improvements to public transportation can alleviate congestion issues. Earlier this month, his administration proposed raising the hourly fees on most meters in the city from $1.25 per hour to $2 per hour.

"I think what we have to do is continue to work with the state to work on public transportation," Walsh said. "If people think public transportation works and gets them from point A to point B — and they can do it in good time and not be delayed and they think it's a good, safe, clean system — you'll see less people driving."