WASHINGTON — Democratic lawmakers unveiled bicameral legislation Tuesday that would force the Federal Communications Commission to ban fast lanes on the Internet.

The proposal, put forward by Senate Judiciary Committee chair Patrick Leahy, D-Vt., and Rep. Doris Matsui, D-Calif., requires the FCC to use whatever authority it sees fit to make sure that Internet providers don’t speed up certain types of content (like Netflix videos) at the expense of others (like email). It wouldn’t give the commission new powers, but the bill — known as the Online Competition and Consumer Choice Act — would give the FCC crucial political cover to prohibit what consumer advocates say would harm startup companies and Internet services by requiring them to pay extra fees to Internet providers.

“Americans are speaking loud and clear,” said Leahy, who is holding a hearing on net neutrality in Vermont this summer. “They want an Internet that is a platform for free expression and innovation, where the best ideas and services can reach consumers based on merit rather than based on a financial relationship with a broadband provider.”

Leahy and Matsui’s proposed ban on fast lanes would apply only to the connections between consumers and their Internet providers — the part of the Internet governed by the FCC’s proposed net neutrality rules. The FCC’s current proposal tacitly allows for the creation of a tiered Internet for content companies, though the commission has asked the public whether it should ban the practice as “commercially unreasonable.”

“A free and open Internet is essential for consumers,” said Matsui. “Our country cannot afford ‘pay-for-play’ schemes that divide our Internet into tiers based on who has the deepest pockets.”

Because the bill merely directs the FCC to rely on its current authorities, there’s a limit to how effective it could be. An ongoing debate at the FCC is whether it can legally ban traffic discrimination at all. Under the current proposal, the FCC would tacitly allow commercial speed agreements but then review problematic ones on a case-by-case basis, rather than lay down a blanket restriction against what’s called “paid prioritization.”

Consumer advocates have suggested instead that the FCC reclassify broadband as a utility — a decision that would subject Internet providers to greater regulation. But broadband companies have said that even that would not guarantee a prioritization ban’s survival, because of a loophole in the law that allows for some traffic discrimination so long as it isn’t “unjust” or “unreasonable.”

The Democratic bill is another sign that net neutrality is dividing lawmakers along partisan lines. In May, Rep. Bob Latta, R-Ohio, introduced a bill that would prevent the FCC from reclassifying broadband. A Democratic aide conceded Monday that the Leahy-Matsui bill is unlikely to attract Republican cosponsors.

The fact that Republicans control the House make it unlikely that the Leahy-Matsui bill will advance very far. Still, the politics of net neutrality are obscuring the underlying economics at stake, according to the aide, who asked not to be named because he wasn’t authorized to speak publicly.

“People are missing the point,” the aide said. “The point is: Ban paid prioritization. Because that’ll fundamentally change how the Internet works.”

FCC Chairman Tom Wheeler has said that he’s reserving the reclassification option in case his existing plan fails to protect consumers. He has been reluctant to use that option so far, likely because it would be politically controversial. But increasingly, it seems net neutrality is divisive enough without that option.