WASHINGTON — Sen. Lloyd Bentsen (D) of Texas plans to introduce this week a five-year, $72.5 billion tax cut that would focus on tax credits for children, IRAs, and cuts in the defense budget.The tax package "would give you a short-term stimulus for middle-income America that's the worst hit in this situation, and then it would give you the long-term growth: savings," Bentsen said Sunday in introducing the proposal on CBS's "Face the Nation." According to Bentsen, who heads the Senate Finance Committee, the stimulus would come from a $300 tax credit for every child aged 18 and under that lives with his or her relatives. The long-term growth in savings, Bentsen said, would come from the return of tax-deductible individual retirement accounts up to $2,000, with terms for withdrawal to buy homes, pay for education, or cover medical bills. To offset the drop in federal income - as mandated by the budget compromise worked out last year between Congress and President Bush - spending for defense would be cut by 5 percent over five years beginning in 1993, Bentsen said. While Bentsen predicted that members of both parties would get behind his proposal, Republicans speaking on other television talk shows Sunday seemed cool to the idea and talked more of their proposals.