Sen. Al Franken urged Federal Communications Commission Chairman Julius Genachowski to heavily revise proposed rules for Internet service providers in a letter sent to the chairman Friday.

The FCC is planning to vote on a Net neutrality proposal on Dec. 21 that would bar broadband Internet providers from discriminating against lawful Internet traffic, but potentially allow them to create priority service for websites — at a higher price — that wish to give their customers faster speeds for things like streaming video.

Franken said the proposal needs "major revisions" and "may do more harm than doing nothing at all."

The proposed rules create "an Internet 'fast lane' for big companies that can afford it," Franken wrote. "Paid prioritization is the antithesis of net neutrality."

Franken has been fierce advocate of Net neutrality, labeling it the "First Amendment issue of our time." He's called for the FCC to adopt Net neutrality rules that bar Internet providers from creating tiered service or blocking Web traffic.

In Friday's letter, Franken also raised concerns that mobile Internet was not going to be as restricted as broadband, leaving the door open for Internet companies to circumvent the rules.

"The draft Order would effectively permit the blocking of lawful content, applications, and devices on mobile Internet connections — and would in fact fail to impose any non-discrimination protections for users of mobile Internet services." Franken wrote.

Franken's Net neutrality critics say that strict Net neutrality rules would restrict private companies and stifle their ability to innovate.