Since the earliest days of journalism, the press has been fighting for survival against the powers of oppression. The Sandinistas, for example, shut down La Prensa. But sometimes the enemy is closer to home.

Last month several members of the U.S. Senate launched a sneak attack on the First Amendment by furtively passing legislation that forbids the Federal Communications Commission from considering waivers to the rule prohibiting cross-ownership of a newspaper and a television station in the same market. The target of this underhanded assault on open government was Rupert Murdoch, owner of the the New York Post and WNYW-TV in New York, and the Boston Herald and WFXT-TV in Boston. The purpose of the FCC regulation is to keep one owner from dominating competing news media. The purpose behind sneaking the FCC amendment through Congress was to avoid detection of an outrageous mugging of the public interest.

Instead of debating the issues on the Senate floor, thus giving New York Sens. Alfonse D'Amato and Daniel Moynihan a chance to express their opposition, Sen. Ernest Hollings of South Carolina acted in the dead of night. He introduced the anti-Murdoch legislation directly to a House-Senate conference committee. By the time our New York delegation discovered that Hollings had short-circuited the legislative process, it was too late.

For some strange reason, however, Hollings did remember to notify Sen. Edward Kennedy of Massachusetts that he was introducing a bill "aimed directly" at Rupert Murdoch, who would be forced to sell his papers in Boston and New York. Later it turned out that the trail of ink-stained footsteps led straight to Ted Kennedy's door and that he himself had encouraged Hollings to do what he did.

It's not hard to figure out why. Murdoch's Boston Herald, like his New York Post, generally supports the conservative end of the political spectrum. The Herald has been a constant critic of the liberal Kennedy. It's not surprising he'd like to see it sold to another owner. What is surprising, however, is that a staunch advocate of liberalism would subvert liberal principles in the name of hidden self-interest.

I happen to like both Rupert Murdoch and the New York Post. There are those who will cynically suggest that I am supporting Murdoch because he supported me. Let me make it clear that if this unfair action had been taken against the Amsterdam News -- a paper that weekly calls for my resignation -- I would respond in exactly the same way. The overriding issue is not whether you like the Post and the Herald. The issue is whether or not we are going to stand by and allow our freedom of the press to be abridged and abrogated by veiled manipulations in the back rooms of Congress. If a fascist gang broke into the Post and burned the building to the ground, we would be up in arms at this blitzkrieg against the press. Should we be any less concerned if the same result is achieved by secret deals in Washington?

Under previous regulations, the FCC had the latitude to make exceptions to the rule prohibiting one owner from running a broadcasting station and a newspaper in the same area. Such waivers recognized that conditions vary from city to city. In New York City, for example, The New York Times owns WQXR radio. The Daily News and WPIX-TV are both owned by the same company. These cross-ownerships are permitted because they were grandfathered in when the new FCC regulations took effect. Does anyone seriously believe that such ownership in any way constitutes a monopoly of the media? Of course not. We have dozens of radio stations and dozens of television and cable channels that represent every conceivable facet of public opinion. In such a market, worries about monopoly of the press are unwarranted.

The former FCC rule recognized that hard-and-fast laws against ownership of a newspaper are likely to be incompatible with the First Amendment of the U.S. Constitution, which guarantees freedom of the press. Waivers were appropriate when local conditions called for them. Rupert Murdoch was appealing for such waivers in New York and Boston. I think he deserves them. New York City has four daily papers to serve a population of more than 7 million. Among them, the four dailies cover the complete range of news stories and political viewpoints. Were we to lose any one of them, it would be a blow to the entire city.

It should be noted that the Post has been running a large annual deficit. Rupert Murdoch is keeping it going anyway. I think he deserves our thanks and gratitude. If the Post and the Herald succumb to this submarine attack from Washington, thousands of employees could lose their jobs.

I am calling upon every presidential candidate, Democratic and Republican, and upon President Reagan himself to urge Congress to reconvene immediately and undo this deplorable act. I will support no candidate -- in either the primaries or the general election -- who does not join in this defense of the First Amendment. I urge others to take the same stand.

The Kennedy-Hollings measure has defamed our legislative process and undermined our freedom of the press. The anti-Murdoch bill is a direct attack on a cornerstone of American liberty. It must be repealed. Let the FCC make its determination based on the merits of the case. Kennedy and Hollings should recognize the harm they have done and lead the effort to overturn their ill-advised legislation. Rupert Murdoch is an American citizen. The fact that he came from Australia does not mean he deserves to be the victim of a kangaroo court in the halls of Congress.

The writer is mayor of New York City.