The Federal Communications Commission has, as expected, voted along party lines to approve the demand of Rupert Murdoch and other communications-industry moguls for a loosening of limits on media monopolies in American cities.

Now, the real fight begins.

There was never any doubt that FCC chair Kevin Martin, a Bush-Cheney administration appointee and acolyte, would lead the two other Republican members of the commission to a 3-2 endorsement of a move to begin dismantling the historic “newspaper/broadcast cross-ownership” ban which has long served as the only barrier to the buying by one powerful individual or corporation of newspapers, television and radio stations and other media outlets in a community.

The two dissidents on the commission — Democrats Michael Copps and Jonathan Adelstein — cast their expected votes against Martin’s plan to allow a company in the 20 largest media markets to own both newspapers and radio and television stations. The Martin plan also opens up smaller markets to monopoly exploitation allowing firms to apply for a waiver of the cross-ownership ban.

Arguing that the commission was bowing to pressure from media conglomerates without beginning to study the likely impact on local news coverage, minority ownership and other supposed concerns of the FCC, Copps told his fellow commissioners, “Today’s story is a majority decision unconnected to good policy and not even incidentally concerned with encouraging media to make our democracy stronger. We are not concerned with gathering valid data, conducting good research, or following the facts where they lead us.”

Copps said he had little doubt that Martin and the other two Republicans would move quickly to waive what remains of the cross-ownership ban and begin approving mergers in communities large and small across the whole country.

Martin’s move, while very much in line with the Bush’s administration’s radical pro-corporate agenda, goes against every signal the FCC has gotten from Congress, which is responsible for establishing regulations regarding the ownership of the public’s airwaves.

“The FCC has never attempted such a brazen act of defiance against Congress,” argued Adelstein, in a passionate condemnation of the commission’s actions. “Like the Titanic, we are steaming at full speed despite repeated warnings of danger ahead. We should have slowed down rather than put everything at risk.”

The response to that risk must come from Congress.

Before the vote, 26 members of the Senate — a quarter of the chamber’s members — notified the commission that they would “immediately move legislation that will revoke and nullify the proposed rule.”

The senators making that promise are the key players on communications policy in the chamber, including Commerce Committee chair Daniel Inouye, D-Hawaii, and the vice chairman of that committee, Ted Stevens, R-Alaska. So they can make the move.

But they will need the full and aggressive support of Democratic leaders in the Senate and House to push back with the force necessary to counter an expected veto by President Bush.

This is one fight where citizen action will matter. Key Republicans such as Stevens and Mississippi’s Trent Lott, the party’s number two man in the Senate, are in complete support of the move to overturn the FCC vote. It is possible to build a broad coalition. But there can be no wavering by the Democrats on this front.

Indeed, they must make this a national issue. And the way to do that is by talking it up where it cannot be ignored. All four Democratic senators who are seeking the presidency signed the letter pledging to revoke and nullify the FCC decision.

Now, New York’s Hillary Clinton, Illinois’ Barack Obama, Connecticut’s Chris Dodd and Delaware’s Joe Biden need to put the issue of media monopoly front and center in Iowa and New Hampshire. Of course, they can and will talk about other issues. But if they are not talking about the fundamental threat to diversity of media ownership in American communities and the country as a whole, they will be failing to use the most powerful bully pulpit in the fight against the monopoly on communication that represents the single greatest threat to the battered democratic discourse of a country where the public’s right to know cannot take this hit and survive.