Media companies and consumer groups don't agree on many things, but distaste for Federal Communications Commission Chairman Kevin Martin's effort to rewrite the nation's media-ownership rules appears to be one of them.

They approach the issue from opposite sides — media companies want even looser limits on what broadcast properties they can own, while activists say Mr. Martin went too far. Both are digging in for a contentious two-week battle at the FCC, which is scheduled to rule on Mr. Martin's plan Dec. 18.

Mr. Martin proposes allowing media companies to own both a newspaper and television station in the nation's 20 biggest markets. Waivers allowing cross-ownership of newspaper and broadcast properties in smaller markets would be considered on a case-by-case basis. Consumer groups argue this will lead to consolidation, with less local news and less diversity of voices. Media companies, on the other hand, want looser rules, arguing that the Internet provides more competition in most markets.

As a bipartisan collection of lawmakers and media activists fights to put the brakes on the proposal, Mr. Martin's skills as a political deal maker will be tested. The FCC chairman says he intends to move ahead, despite uncertainty that his fellow Republican commissioners will give him the support he needs to win. Behind the rhetoric, however, he has already begun quietly laying the foundation for a likely challenge in court.

Yesterday, Mr. Martin came under attack at a House hearing on the matter. Democrats accused Mr. Martin of rushing through changes without giving the public sufficient opportunity to comment on his plans, and Republicans endorsed his overhaul but said he didn't go far enough. The Republicans' concerns have been echoed by Clear Channel Communications Inc., Media General Inc. and other companies that had hoped Mr. Martin would significantly loosen caps on radio and broadcast ownership.

Mr. Martin agreed he could have gone further but said he recognized the need for caution. "I think the commission should take what is obviously a controversial step gradually," he said, and first deal with easing cross-ownership prohibitions in bigger markets, "where there is a plethora of voices," before looking at smaller media markets.

On Tuesday, a Senate committee approved legislation that would require Mr. Martin to slow the media-ownership review by as many as six months — a move that would put the matter in the spotlight close to the presidential election and almost surely delay a vote until a new administration takes over. The bill isn't expected to pass Congress in the next two weeks but was designed to send a message to Mr. Martin that he should delay the vote.

Compared with his predecessor, Michael Powell, Mr. Martin has proposed relatively modest changes to the nation's media-ownership limits, allowing media companies to own a newspaper and a television station in the top 20 markets in the country as long as the station isn't one of the four most popular in its market.

Media activists complain that Mr. Martin's cross-ownership rule is riddled with loopholes that would allow far more consolidation in smaller markets.

In 2003, the FCC, then led by Mr. Powell, narrowly voted to lift cross-ownership restrictions, ease limits on local broadcast ownership and raise the national broadcast ownership limit to 45% of the audience. The 45% provision was later knocked down by Congress. The rest was challenged in the Third Circuit Court of Appeals. In June 2004, the court ruled that the FCC hadn't justified changes to the rules and kicked them back to the agency.

This time, Mr. Martin has already quietly begun laying the groundwork for another legal challenge. Last week, the FCC took an unconventional route to approving the temporary waivers that will allow Sam Zell's $8.2 billion buyout deal of Tribune Co. to move forward. Instead of granting temporary waivers, the FCC actually denied Tribune's request. The company gets a two-year extension on its current waivers only if it sues the FCC about the denial.

That maneuvering would likely put the issue of media-ownership limits before the federal Court of Appeals for the District of Columbia, which generally gives the FCC more deference than other appeals courts.