THE weekend start of major ground fighting solidified the Gulf war as the dominant issue this year in Congress and around the country. Further, the war can be expected to be the No. 1 issue on Capitol Hill well after the fighting dies down, when questions of military costs and postwar assessments edge their way onto the congressional agenda. Already the cost question has moved onto the Hill's radar screen, with the administration request late last week for $15 billion to pay America's share of war costs, beyond what other coalition members provide. The administration estimated the total cost of the war could reach $77 billion. Congress has given support both to the US troops in the Middle East and to President Bush for the past six weeks, ever since it narrowly endorsed the president's willingness to eject Iraqi troops from Kuwait by military means, in accordance with the UN Security Council resolutions. No sooner had Mr. Bush officially announced the start of the ground campaign than members of Congress voiced their support. Sen. Orrin Hatch (R) of Utah said the president had done ``what's right. He is trying to stop worldwide problems by doing something now.'' And Rep. Lee Hamilton (D) of Indiana said the president had taken ``the appropriate approach'' by focusing ``on getting Iraq out of Kuwait.'' Even before the ground campaign had begun congressional leaders were conceding that the war would dominate legislative debate this year. At the same time they were careful to point out that Congress would also continue to work on major domestic issues: transportation, poverty, education, energy, housing, campaign finance reform, the economy, health insurance. The day before the war began last month, Senate majority leader George Mitchell (D) of Maine signaled his party's determination to move ahead on domestic issues, war or no war: ``As important as the Gulf crisis is, we cannot turn our backs on the other business of the nation.... We have crises here at home as well.'' Yet even as Congress worked on domestic issues there was no mistaking the fact that in the forefront of many members' thoughts was the Gulf war and the half-million American troops now deployed. In recent days Congress or its committees have discussed a resolution to urge Americans to display the flag, a cost-of-living raise for disabled veterans, a tuition-credit proposal for students sent to the Gulf with the military, a bill to require the Pentagon to report regularly to Congress on the costs of the war, and a measure to prevent the military from sending both of any child's parents to the Gulf. Rep. Clay Shaw (R) of Florida, the flag resolution's sponsor, said that by approving the measure the House would send military personnel in the war zone ``a strong, clear message that the American people are united in their resolve to support our men and women in the Gulf.'' As evidence of the support that Congress has been feeling for the troops, the House overwhelmingly approved the resolution. Symbolism is all very well, said Rep. Craig Washington (D) of Texas, but ``we must also support our troops when they come home.'' He called on the Congress and the nation, so willing to aid US soldiers during war, to ``give substantive support to them by providing jobs, housing, educational assistance, health care, and child care'' through a Persian Gulf Bill of Rights, after they return. In recent days individual members of Congress have also brought up the war in a series of comments on the floor of the House and Senate. Rep. Bob McEwen (R) of Ohio sharply criticized CNN's Peter Arnett, who has been reporting from Baghdad under Iraqi censorship since the beginning of the war. Representative McEwen urged the newsman, whom he called ``Baghdad Pete,'' to ``let us have a little news about what has been going on in the war zone, and not just the propaganda that Baghdad manipulators want to have spread across the American television.'' Rep. Porter Goss (R) of Florida told the House that he was ``amazed by the extensive efforts of my constituents to express their support for our troops in the Persian Gulf.'' Rep. Christopher Cox (R) of California criticized Soviet President Gorbachev's peace initiative, and urged his colleagues ``soundly to reject Gorbachev's thinly disguised attempt to save Saddam Hussein.'' -PATHNAME- /usr/local/etc/httpd/plweb/DBGROUPS/paper/database/tape/91/mar/week10/amood.