John Oros, 61, a double-amputee and a veteran of World War II, has a message for a handful of congressmen and senators who are under pressure by lobbyists to water down a key piece of 1983 housing-reform legislation:

"I gave my legs to my country," Oros said from his wheelchair in his tiny, Bradenton, Fla., efficiency apartment. "I would give them again today. But I don't think it's right that I should be thrown out on the street July 18 just because I own a two-pound toy poodle that doesn't bother anybody."

Oros is one of the tens of thousands of elderly and handicapped Americans who could be directly affected by a series of closed-door negotiations that took place on Capitol Hill last week.

Pushed by lobbyists for landlords who own subsidized rental-housing buildings, key senators agreed to severely weaken legislation that would allow elderly and handicapped tenants the right to own a pet in federally assisted projects, under strict regulations.

Originally sponsored in the Senate by Sen. William Proxmire (D-Wis.), the legislation is part of the principal 1983 housing and community development bill (S. 1338). The legislation would:

* Prohibit private and public owners of apartment projects who receive federal financing assistance from enforcing total bans against ownership of "common-household pets" by elderly and handicapped tenants.

* Empower apartment-building owners, nonetheless, to create tough rules and standards for keeping pets in buildings. Among the rights of landlords, according to the bill, is the power to "require removal of any pet whose conduct or condition is duly determined to constitute a nuisance or threat to the health or safety of the other occupants of such housing or of other persons in the community where such housing is located."

The concept of the original bill "was to take a reasonable middle road on this issue," in the words of a staff aide to Proxmire. "We recognize that you can't simply guarantee every elderly or handicapped person the right to keep a pet, without concern for what pets can do to a building."

On the other hand, "We wanted to end the absolutely unfair situation that you find in virtually every federally assisted apartment project across the country," the aide said. The landlords ban pets under any circumstances, despite the abundance of medical evidence that pets are a tremendous health benefit to elderly and handicapped people living alone.

There are more than 3.7 million federally subsidized rental units in the United States, many of them containing elderly or handicapped tenants, according to the Department of Housing and Urban Development.

Proxmire's 1983 "pet amendment" was derived several months ago from a bill sponsored in the House by Rep. Mario Biaggi (D-N.Y.). Biaggi feels so strongly about repeated evictions of elderly and crippled tenants for ownership of small pets that he has sought to deny funds to any private or public owner of subsidized housing who does so.

Proxmire, however, felt that funding cut-offs would be considered extreme by his colleagues. He offered his more moderate version instead, and received bipartisan support on the Senate Banking Committee for its inclusion in the 1983 housing bill.

That success triggered alarm bells at the offices of Washington-based lobbies representing landlords of low-income housing projects. Groups such as the National Leased Housing Association and the National Association of Housing and Redevelopment Officials "went bananas over pets," said a Senate Banking Committee staff assistant.

"They didn't bother to read the language that gives landlords all the leeway they need to control pets. So we suddenly began getting angry letters and calls from building owners who claimed we wanted Doberman pinschers and Great Danes prowling their halls, knocking over all the little old ladies in wheelchairs."

Key senators, such as Housing subcommittee chairman John G. Tower (R-Tex.)--who is running for reelection this fall--also came under pressure from the lobbyists. And as so often occurs in the federal legislative process, key portions of the bill were effectively gutted without a formal meeting of the subcommittee that originally passed it in public session.

Tower, who earlier had declared his absolute support for the bill--noting he is a kitten owner himself--told Proxmire he would amend the bill during floor debate June 21. Aides to Proxmire finally agreed to modifications that give building owners the power to set standards for pet ownership that are so tough that few, if any, low-income tenants would choose to exercise their new legal rights to do so.

Under the revised language, for instance, landlords can impose house rules requiring pet-owning tenants to defray all "potential financial obligations" arising from the presence of their pets on the premises.

Under the bill, a building owner could require tenants to put up security deposits--such as two months rent or more--before they could keep a pet in their unit.

Owners would be free to devise an almost limitless variety of other regulations on standards of pet care, size of pets and the "density" of the building. The net effect would be a gauntlet--one so forbidding that it would negate Congress' apparent legal guarantee regarding pet ownership.

In the words of the executive director of the National Leased Housing Association, Janet Charlton, "Our real objective is to kill the whole pet thing. The Senate language takes us much closer to that" result.

For tenant Oros, passage of the Tower amendment in its current form could amount to a legislative charade. Oros, who was hit with an eviction notice from his landlord after he bought a seven-inch-long poodle, said 10 of the 11 other tenants in his building have signed a petition asking that he and his dog be permitted to stay on.

His landlord, however, has refused to budge from the no-pet rule, even after a phone request from Proxmire's office.

"I don't think the no-pet rule would really change" under the newly revised language pending on Capitol Hill, Oros said.

The full Senate will take up the watered-down pet amendment sometime after the July 4 recess. Oros, whose eviction notice takes effect in three weeks, hopes the lobbyists' backdoor tactics backfire.