Sen. Patrick Leahy (lef) (D-Vt.) confers with Sen. Sheldon Whitehouse (R) (D-R.I.) prior to a Senate Judiciary Committee hearing Sept. 17, 2014, in Washington, D.C. (Win McNamee/Getty Images)

Democrats are reviving a bill meant to block Internet providers from speeding up or slowing down some Web sites over others — part of a wider political tussle over net neutrality that's drawn in the White House, congressional Republicans and the Federal Communications Commission.

The bill, backed by Sen. Patrick Leahy (D-Vt.) and Rep. Doris Matsui (D-Calif.), would instruct the FCC to ban what's called "paid prioritization," or the commercial deals that would allow broadband providers to give some Internet traffic preferential treatment over their networks. Critics of paid prioritization say it could give an unfair advantage to large, established companies that can afford the fees, cutting out smaller start-ups and small businesses.

Here's a copy of the bill, which was first introduced last year.

As the new year begins, expect a flurry of moves and countermoves aimed at preemption. Republicans are expected to unveil legislation this month to get ahead of the FCC's proposal, which the agency confirmed will drop next month.

By reintroducing legislation before a Republican version emerges, Democrats could keep Republicans from attracting liberals to their side. A Republican bill would likely give the FCC clearer, explicit authority to regulate net neutrality — something that Democrats might like — but, crucially, prohibit the agency from using its strongest legal tool, known as Title II of the Communications Act.

Top Republicans have their own challenges ahead, however. Some of the party's most conservative members are opposed to any net neutrality rules, including through legislation — making it that much more important to get some Democratic support. And even if the GOP manages to pass a bill, it still must overcome a potential presidential veto. In November, President Obama issued a rare White House statement on the future of the Internet, calling for clear net neutrality rules and urging the FCC to invoke Title II. It's unclear whether Obama would compromise with congressional Republicans if presented with a bill that gives him everything except Title II.