For the first time since the Reagan era, a bipartisan consensus has emerged for a major defense buildup, as Congress and the administration rapidly move toward agreement on a substantial increase in military spending.

With U.S. forces stretched thin throughout Europe, Asia and the Middle East and troubling reports from the Kosovo war of shortages of missiles and jet fighter parts, the White House and GOP leaders agree that it's no longer a question of whether to beef up the military but by how much.

"There is no question that we have underspent on defense," said Sen. Larry E. Craig (Idaho), the third-ranking Republican leader in the Senate. "We're burning up equipment, we're burning up personnel, we're putting tremendous stress on the system, and we're going to have to fix that or we create a risk for our country in future commitments."

Because Congress seems determined to hold down overall spending -- and perhaps even provide a tax cut -- the defense binge will almost certainly come at the expense of domestic programs, moderate and liberal legislators warn.

Some Capitol Hill veterans also fear a "bidding war" on defense, as lawmakers trip over one another to show their allegiance to a vigorous military; just this month Congress approved a funding package for the Kosovo war that was nearly double the $6 billion President Clinton requested.

But with the war in Kosovo stretching on and the Clinton administration now conceding the need for military enhancements -- after resisting for years -- momentum for a buildup appears irreversible. On Thursday, the Senate voted overwhelmingly to approve a defense authorization bill that boosts "real" defense spending, adjusted for the effects of inflation, for the first time in 15 years.

The House postponed action on its version of the legislation because of an internal Republican dispute over Kosovo war policy this week, but lawmakers expect it will follow suit after the Memorial Day recess.

"The widening gap between the nation's global security obligations and the resources necessary to meet these obligations . . . has thrown into stark relief the reality of the danger of what it means for our military forces to have to do more with less," said House Armed Services Committee Chairman Floyd Spence (R-S.C.).

Clinton's proposed budget would boost defense spending overall by $112 billion over the next six years, including funds enough for a 4.4 percent across-the-board pay raise, improved retirement benefits and a substantial boost in weapons procurement. Republican leaders say that's a start, but not nearly enough, and have proposed at least $25 billion more in spending over the same period.

For the fiscal year starting Oct. 1, the Republicans' budget would spend $288.8 billion on defense, or $8 billion more than Clinton's request, and provide a slightly bigger pay raise of 4.8 percent.

Some Republicans note that Clinton's budget falls $70 billion short of what military leaders say is essential over the next six years. Even so, Clinton's plan would provide more in overall funding than the Republican plan over the coming decade. That's because GOP leaders are also pushing for a substantial tax cut that would cut into defense spending down the road.

Pressure has been rising for a Pentagon buildup for several years, with GOP politicians frequently complaining that the military was suffering from a sharp decline in morale and "readiness" for combat. The administration disputed such criticism, until last September, when Gen. Henry H. Shelton, the chairman of the Joint Chiefs of Staff, testified before Congress that U.S. forces "are showing increasing signs of serious wear."

Even so, some liberal and moderate lawmakers held out hope that they could stop the bandwagon. In a recent letter to 300 advocacy groups, Democratic lawmakers, including Rep. Barney Frank (D-Mass.) and Sen. Paul D. Wellstone (D-Minn.), sounded a blunt message: Either help to slow the bandwagon for more Pentagon spending or suffer the loss of billions of dollars in virtually every major domestic program, from environmental cleanup to social services to law enforcement.

The reason is that under the 1997 balanced budget deal, overall spending in the coming year for defense and domestic programs, other than entitlements like Social Security and Medicare, would be capped roughly at this year's level. In this new zero-sum game, the only way to increase defense spending substantially is by cutting into domestic programs -- by as much as 20 percent to 30 percent.

But the day after the Democrats dispatched their letter of warning on March 23, NATO bombs began dropping on Yugoslavia. The combination of the war and the drumbeat on Capitol Hill for more defense spending swamped the Democrats and ended any serious effort to block additional defense spending.

"That absolutely knocked us off track," Wellstone recalled.

From that point on, noted Frank, liberals began to acknowledge the futility of trying to mount a frontal attack on the defense budget. Instead, they would try to work around the edges, including joining forces with conservatives in arguing for a gradual reduction in U.S. forces in Europe to force Western allies to assume more of the cost of their own defense.

"Kosovo has made it harder to cut [defense] from the given level of commitment," Frank said. "But it has increased awareness to the extent to which we are overcommitted where we don't have to be."

Kosovo clearly is the wild card in the renewed defense debate, and many defense hawks are confident it will provide added impetus to Congress to approve huge long-term spending increases. "When we have a war like the one in Kosovo and Serbia, it can't help but call attention to the [military] shortfalls" that need to be corrected, said House Appropriations Committee Chairman C.W. Bill Young (R-Fla.).

Indeed, some of the more glaring examples of shortages of sophisticated missiles, bombs and airplanes are being used by some to challenge the assumptions underlying the Pentagon's professed capability to simultaneously wage war on two fronts. "If we do not continue to have increases in our defense spending, then we will suffer a reoccurence of the hollow military that I experienced when I first came to the Senate in the 1970s and early '80s," said Senate Armed Services Committee Chairman John W. Warner (R-Va.).

But Steven M. Kosiak, a defense analyst with the Center for Strategic and Budgetary Assessments, cautions that there is no assurance that the looming defense spending increase will last indefinitely, particularly if the war against Slobodan Milosevic's forces turns out badly.

"In the short term, everyone is gung ho and there's a feeling `We've got to help support the military, we've got to pay for this operation, we've got to be strong,' " Kosiak said. "But over the longer term, I think the implications for defense are unclear. It depends on how [the war] turns out, and it depends on how it is interpreted by people."

CAPTION: More for the Military (This chart was not available)