Washington ? Republican leaders in Congress are hoping to complete a bill to curb the growth of student loans, Medicaid and other benefit programs before Christmas, though they may delay extending tax cuts until next year.

But staff aides and lobbyists are skeptical about the prospects of finishing work in the next few weeks on five-year spending cuts of up to $50 billion.

Failure to deliver would disappoint GOP loyalists eager to see their party burnish its budget-cutting credentials, and would push the contentious issue into January or February, muddying the agenda for 2006.

The House returns for a scheduled two-week session on Tuesday; senators do not come back until next week.

House Speaker Dennis Hastert, R-Ill., and Senate Majority Leader Bill Frist, R-Tenn., say they are “deeply committed to restraining spending” and hope to finish the cuts before Christmas.

The chances for completing an accompanying tax cut bill are more doubtful as Congress wraps up a fall agenda that was complicated by Hurricane Katrina.

“On the spending side I believe we will finish,” Frist said. “I cannot predict on the tax side.”

The centerpiece is the budget cut bill, the first attempt in eight years to check the growth of Medicaid and other benefit programs. Their costs rise automatically each year to reflect inflation and population growth, unless Congress reduces them.

The House and Senate have approved separate budget bills that take divergent approaches:

¢ the House would trim spending by $50 billion over five years, compared with almost $35 billion in the Senate’s version.

¢ the Senate would put those savings into initiatives such as college aid and maintaining physician reimbursements under Medicare. The House measure contains far less spending.

¢ the Senate voted to go ahead with drilling for oil in a wildlife refuge in Alaska. GOP leaders in the House were forced to scuttle that idea to get the budget measure approved. Powerful senators such as Ted Stevens, R-Alaska, and Pete Domenici, R-N.M., are insisting that a final compromise bill include the drilling measure.

“Because these bills are so fundamentally different, the next two weeks will look a lot like a two-minute drill in football,” said GOP lobbyist Jack Howard, a veteran of Capitol Hill and the Bush White House.

“They’re going to have to drive the length of the field and a lot of things are going to have to happen very fast,” he said.

Added Tom Kahn, Democratic staff director for the House Budget Committee: “I think they’re going to have one heck of a time getting this thing done by the end of the year, and I would be surprised if they could do it – very surprised. There’s just too many difficult and controversial issues.”