President Bush's 1991 defense budget could be cut nearly $6 billion through reductions including Star Wars spending and delaying a plan to put MX nuclear missiles on rail cars, the chairman of the Senate Armed Services Committee said Friday. Sen. Sam Nunn, D-Ga., called for a military budget of $297 billion to $298 billion for the fiscal year that begins Oct. 1. Bush wants a $303 billion budget, including an additional $1 billion for the Strategic Defense Initiative, commonly known as Star Wars. ``Assuming SDI is redirected into a coherent and rational research program, I believe it should be funded at roughly the current appropriated level,'' Nunn said in a speech on the Senate floor. Congress approved about $3.8 billion for the anti-missile shield in 1990's $296 billion defense budget. The SDI total marked the first reduction in the program in six years. Nunn's overall budget proposal is about $1.5 billion more than the cut adopted Thursday by the House Budget Committee and some $6 billion higher than the figure suggested by Senate Budget Committee chairman Sen. James Sasser, D-Tenn. ``I think the fight will be to try to keep defense even at the levels I'm talking about,'' Nunn said. He projected defense savings of about $3 billion to $3.5 billion this year from the changes in the strategic programs and between $20 billion and $30 billion over the next five years. Nunn's comments on the budget were the first by the powerful chairman of the Armed Services Committee. He is the leading defense expert among conservative Democrats. Elsewhere on Capitol Hill, White House budget director Richard Darman dismissed all Democratic defense proposals and argued that lawmakers' affection for pet defense project in their districts will prevail over the cuts. ``As it gets much more clear what it means for particular congressmen's districts, you'll see the political system, independent of defense strategy, start to put a bottom on that defense cut,'' Darman said. Nunn called his budget range a ``realistic and responsible target.'' He said there should be a delay in placing multiple-warhead MX missiles on railroad cars and criticized the purchase of trains while the Pentagan is still conducting tests. The Bush budget calls for $2.2 billion to put 50 MX missiles on rail cars. Sens. Carl Levin, D-Mich., and James Jeffords, R-Vt., introduced legislation Friday that would cut $1.6 billion of the administration proposal for the MX. That total represents all the procurement and military construction funds in Bush's budget for MX. ``The MX rail-garrison funding plan is a classic example of the flawed `buy before you fly' policy that has cost the country so much money in recent years,'' Levin said in a speech on the Senate floor. Nunn reiterated his support for the single-warhead Midgetman missile, but suggested deployment in existing silos with mobile launchers a later option. He repeated his opposition to development of a new short-range nuclear missile in Europe and questioned buying a new Trident submarine each year and Trident D-5 missiles with nuclear warheads in short supply. Nunn reserved comment on the B-2 stealth bomber until after Defense Secretary Dick Cheney briefs members of Congress on the Pentagon's review of major aircraft programs. However, Nunn said the B-2 program of 132 planes at a cost of $72 billion ``must be made more affordable.'' Nunn called for slashing Bush's defense budget authority to $289 billion to $291 billion, about $18 billion less than the president has proposed for fiscal 1991. Because budget authority represents the amount that can be spent over several years _ such as in a long-term contract to purchase warships _ the cut would force reductions in future Pentagon spending plans.