Chicago ? President Bush put his weight behind growing momentum in Congress to pass a Medicare prescription drug plan Wednesday, and the top Senate Democrat said such a plan now seems likely to win approval.

As House Republican leaders labored over the details of their own version of the legislation, GOP aides said it included a provision to save roughly $18 billion over the next five years by holding down increases that hospitals receive to offset the effects of inflation.

The legislation also calls for Medicare recipients to pay higher costs for doctor and out-of-hospital expenses by raising the annual deductible, now set at $100, these aides said, speaking on condition of anonymity.

Bush challenged lawmakers to send him a bill by the Fourth of July.

“We’ve got a growing consensus in both houses of Congress, and in both political parties, a consensus that our seniors need more choices and better benefits including prescription drugs,” he told the Illinois State Medical Society.

“The time is right for progress,” he said. “I’m here to urge Congress not to miss the opportunity.”

Both the House and Senate bills would offer prescription drug coverage to Medicare beneficiaries, as well as a new managed care option.

As Bush promoted Medicare overhaul on the road, support appeared to be building in Congress.

“I think it will pass,” Senate Minority Leader Tom Daschle, D-S.D., said.

But Democrats remained divided on GOP-backed plans moving through both chambers, with many suggesting they still don’t go far enough to meet the needs of the elderly.

And Daschle and other Democrats said they would seek several changes to strengthen the bill, including one that would close a gap in coverage for Medicare recipients who spend more than $3,450 and less than $5,300 in any one year on prescription drugs.

At the same time, representatives of the nation’s governors wrote to key lawmakers during the day, seeking a change in the provision of the legislation that leaves states responsible for the costs of prescription drug benefits for poor elderly who qualify for Medicaid as well as Medicare.

“The nation’s governors oppose this approach. It is not good health policy and it is not good precedent,” wrote Govs. Paul Patton, D-Ky., and Dirk Kempthorne, R-Idaho.