Medicare Plan Raises the Cost For the Affluent
Congress is considering change in Medicare that would require affluent people to pay higher premiums than other beneficiaries; Republican proposal is gaining unexpected support from some Democrats, who have opposed idea in past but now say they are receptive to it as way to avert Medicare cuts; most of the 40 million Medicare recipients now pay same premium of $58.70 a month; AARP, labor unions and some liberal Democrats say levying extra charge on some beneficiaries would undermine universal nature of program; discussion comes amid efforts to reach agreement on bill to overhaul Medicare and add prescription drug benefits (M)