The Clinton Administration today fired its first big post-election salvo against the advancing Republicans and their agenda. Health and Human Services Secretary Donna Shalala said the GOP's plan to slash welfare benefits will cut off aid to 5 million children now receiving money, without providing them an adequate alternative. Shalala was referring to a legislative package favored by Republicans that will limit cash welfare and housing benefits to teens who have children out of wedlock. Soon-to-be Speaker Newt Gingrich (R-Ga.) has said that children in these circumstances could be taken from their homes and raised in orphanages or foster homes. However, Shalala says an analysis of the Republican plan shows that states would receive enough money to establish fewer than 9,000 slots in group homes -- enough for less than 1 percent of children who would be dropped from the rolls.