Net neutrality is making a comeback in Congress.

The issue that emerged from obscurity last spring to derail a broader overhaul of telecommunications law has remained mostly underground on Capitol Hill this year.

But Rep. Ed Markey (D-Mass.), chairman of the Energy and Commerce Subcommittee on Telecommunications and the Internet, is digging up a bill he wrote last year to prevent phone and cable companies from discriminating against certain kinds of Internet traffic — for example, by charging some companies more money for faster access speeds.

A Markey aide said the new bill will closely follow last year’s measure, though details still are being worked out and a packed end-of-year calendar means it won’t get introduced until next month.

If it gains momentum, it will reignite a pitched lobbying battle that last year matched phone and cable companies — established powerhouses in the influence game — against then-untested newcomers: Internet companies like Google and Yahoo, in alliance with bloggers and other online activists, including MoveOn.org.

Markey has been marshalling net neutrality backers in advance of the actual bill. Aides to the Massachusetts Democrat and House Democratic leadership staff huddled on Nov. 2 with representatives from Google, MoveOn.org, Public Knowledge and Free Press, according to several people familiar with the meeting.

“Markey is looping in his natural allies, so the day he offers the bill, we can rally support around it,” said Adam Green of MoveOn.

In tune with the tech-friendly tenor of the bill, Green said he is hoping Markey will record a YouTube video to announce the legislation and ask people to help him gather 100 co-sponsors by urging their lawmakers to support it.

Last year’s bill gained 23 co-sponsors, and when Markey offered a net neutrality amendment to the broader telecom overhaul on the floor, it was soundly defeated, 269-152.

The Democratic takeover has improved the proposal’s odds. Speaker Nancy Pelosi (D-Calif.) was one of the first to sign on to Markey’s bill last year, and she has highlighted the issue on her personal Web site.

Net neutrality boosters also point to a series of recent actions by phone and cable companies they say highlight the need to rein them in.

Over the summer, AT&T censored part of an Internet broadcast of a Pearl Jam concert, silencing lyrics critical of President Bush. The company later apologized, saying they mistook the blocked lyrics for profanity.

Then, in September, Verizon rejected a request from NARAL Pro-Choice America to make the phone company’s network available for a text-message program, citing its right to block “controversial or unsavory” messages. The company reversed course after a story about the decision appeared in The New York Times.

Most recently, last month, Comcast acknowledged delaying some of its users’ Internet traffic in response to a report it was interfering with file sharing by some of its subscribers. The company defended the tactic as necessary to maintain service across the network.

The response did not satisfy consumer groups. A coalition of them asked the Federal Communications Commission to step in and force Comcast to halt the practice. A separate petition asked the agency to fine Comcast $195,000 for every affected subscriber.

Last week, Free Press hosted a conference call for bloggers and advocates to discuss the Comcast issue. On it, Gigi Sohn, president of Public Knowledge, exhorted bloggers to pressure lawmakers to support net neutrality legislation.

And in the Senate, Sens. Byron Dorgan (D-N.D.) and Olympia Snowe (R-Maine), co-sponsors of their own net neutrality bill, have written to Commerce, Science and Transportation Chairman Daniel Inouye (D-Hawaii) requesting a hearing into the matter.

“Every time a Pearl Jam or NARAL moment happens, there is huge energy created throughout the country for net neutrality,” Green said. “With Markey’s bill, we’ll have a legislative vehicle to focus that amazing energy on and urge Members of Congress to support it.”

Markham Erickson, executive director of the Open Internet Coalition, which formed earlier this year to promote net neutrality as part of a broader federal broadband policy, said the “whole idea of an open and interconnected Internet is something we can’t take for granted anymore.”

“That’s what the debate comes down to: Should there be some basic ground rules that you can’t block political speech and degrade content?” he said.

Phone and cable companies counter that they are not blocking access to Web sites, negating the need for the legislation.

“There are many things that Congress can do to make the broadband revolution real for every American, but regulating the Internet under a guise of network neutrality should not be one of them,” Comcast spokeswoman Sena Fitzmaurice said. “We welcome a full exploration of our network management practices, which are designed only to maximize our customers’ Internet experience.”

Tom Amontree, a spokesman for the United States Telecom Association, said he was unaware of the Markey bill and declined to speculate on its impact.

But another telecom lobbyist, speaking privately, said the measure could put frontline Democrats in a bind by forcing them onto the record in a highly energized and controversial debate.