White House Faces Test on Bosnia Troops : Strategy: Plan to send up to 25,000 Americans to enforce peace has met with reluctance from Congress.

With the possibility of a peace agreement in Bosnia-Herzegovina growing stronger, senior Clinton Administration officials are scrambling to devise a strategy that will allay growing congressional fears over sending U.S. troops to help enforce a cease-fire.

Warnings of opposition were sounded clearly this week. Such influential Democrats as Senate Appropriations Committee Chairman Robert C. Byrd of West Virginia and Armed Services Committee Chairman Sam Nunn of Georgia expressed deep misgivings about the proposed deployment of as many as 25,000 American troops to enforce a truce between the factions in Bosnia.

“The President has not even attempted to do the difficult task of building a consensus . . . in Congress to support such a major military operation of unknown duration in a region where the question of our national interest has yet to be defined,” Byrd complained.

Committing substantial numbers of U.S. troops to the “pretty risky business” of enforcing a Bosnian cease-fire will be tantamount to “sliding down a slippery slope” unless Congress debates and approves of the deployment first, Senate Minority Leader Bob Dole (R-Kan.) said at a meeting with Times editors and reporters on Friday.

Echoing Byrd’s concerns, Dole admitted sharing the deep ambivalence that has all but paralyzed the spasmodic debate over Bosnia in Congress this year--an ambivalence that reflects not a lack of concern but a realization that none of the choices facing the Clinton Administration on the Bosnian crisis is going to be simple or pain-free.

While few lawmakers at this stage have said that they are “dead-set” against contributing forces to a NATO-led peacekeeping mission, sending forces to Bosnia under any circumstances “is a very big deal . . . that isn’t going to be easy for anybody to sign on to,” a senior Administration official conceded.

Ironically, it is the prospect of peace--and with it the likelihood that President Clinton will be called on to keep his promise to supply troops to help enforce it--that will force Congress to come to grips with an issue that it succeeded in dodging through 18 months of bitter ethnic and sectarian strife in the former Yugoslav republic.

“As long as the Administration continued to waffle over things like air strikes and lifting the arms embargo on the Bosnians, Congress could fret, but in the end do nothing too,” a senior Democratic foreign policy aide said. “But like it or not, now we’re being forced out of our cocoon. If we’re on the verge of dispatching the brave sons of our voting constituents into the Bosnian quagmire, everybody knows that we’re going to have to debate and vote on it first.”

Already frustrated by the difficulties encountered in the peacekeeping mission in Somalia--a conflict far smaller and less perilous than the one in Bosnia--lawmakers began voicing their misgivings Thursday in closed-door meetings with Secretary of State Warren Christopher, Defense Secretary Les Aspin and other senior Administration officials.

“The Congress has not reached any conclusions” about the deployment, Christopher acknowledged when asked about the consultations. “There are a great many questions that . . . have to be answered before we ask for congressional support.”

Those questions include concerns about who will command the troops, how many will be involved, what the cost will be, how their mission will be defined and, perhaps most important, when and how they will be withdrawn in the event the cease-fire breaks down.

A White House official said the Administration is working on the answers and probably will have some ready by next week, when the congressional debate goes public at a Bosnia hearing chaired by House Foreign Affairs Committee Chairman Lee H. Hamilton (D-Ind.).

And Senate Foreign Relations Committee Chairman Claiborne Pell (D-R.I.) has announced his intention to hold a Bosnia hearing.

The official added that the Administration has given “careful thought” to the conditions for the deployment and has already decided that U.S. personnel must be limited to “less than half” of the estimated 50,000 troops needed for the force. Although operating under U.N. authority, the force will have to remain under the “clear command and control” of NATO, and the rules of engagement will have to be flexible enough to ensure that “American forces are fully able to defend themselves,” the source said.

Another question that still needs to be resolved, however, is how--and by whom--the costs of the mission will be paid.

Gen. John M. Shalikashvili, Clinton’s choice to succeed Gen. Colin L. Powell as chairman of the Joint Chiefs of Staff, told senators this week that maintaining 50,000 NATO troops in Bosnia would cost about $4 billion per year--a figure Byrd, Dole and other lawmakers view with alarm.

Times staff writer Doyle McManus contributed to this report.