The aftermath of Hurricane Katrina has scrambled Congress’ post-recess agenda and calendar, as leaders are frantically reordering their legislative priorities and pushing the anticipated adjournment date back weeks, and possibly more than a month.

Both the House and Senate were already resigned to missing their original departure target of Oct. 1. And with an enormous new set of challenges to tackle in the coming days, House Majority Leader Tom DeLay (R-Texas) said Tuesday: “It’s obvious that we’re going to be here until Thanksgiving.”

The sentiment is similar on the Senate side, where the schedule is even more crowded following the death of Chief Justice William Rehnquist.

“Considering that we have another Supreme Court nominee to do, I think Thanksgiving is realistic [for adjournment], if not after,” said a Senate GOP leadership aide.

In the House, Republican leaders spent much of Tuesday in meetings trying to determine how best to approach Katrina’s aftermath. While sources said issues such as Social Security and immigration were not prominently discussed at those sessions, Members and aides are aware that the heavier workload and the new political environment created by Katrina could change how the House approaches the rest of its agenda.

“We are seriously involved in Katrina, and there has not been a lot of time to figure out where the rest of the agenda falls into place,” said a House Republican leadership staffer.

Another leadership aide said that — as happens often — much of what the House decides to do will depend on what the Senate does, since that chamber’s schedule is even more crowded than the House’s.

“The House is very much capable of multitasking,” said the second aide. “The bigger question is what the Senate is going to be able to swallow.”

The first significant item that could be bumped by Katrina is the budget reconciliation process. Under this year’s budget agreement, authorizing committees have until Sept. 16 to submit proposed spending cuts under their area of jurisdiction, and the House Ways and Means and Senate Finance Committees have until Sept. 23 to finish the overall reconciliation package.

DeLay said Tuesday that he expected those deadlines would be pushed back a week. The issue was set to be officially decided at a meeting between the Majority Leader and House committee chairmen Tuesday night.

On Social Security, meanwhile, the same uncertainties that plagued the issue in the House before the recess persist after Katrina.

While the Ways and Means Committee continues work on a broad retirement security package, GOP leaders have been unable to reach agreement on their tactical approach to the issue. Specifically, senior Republicans have not formed a consensus on whether they should push forward and pass a bill this year even if the Senate would be unlikely to follow suit.

Though Speaker Dennis Hastert (R-Ill.) and DeLay are in favor of moving a bill regardless of the Senate’s plans, GOP sources said some lawmakers are wary of subjecting everyone to a tough vote on a measure that might never reach the president’s desk.

In addition to Social Security and reconciliation, the House will also likely tackle a potentially divisive immigration bill or bills and the remaining appropriations conference reports.

Despite the heavy workload, GOP leaders remain confident they can still accomplish their pre-Katrina goals.

“We can do more than one thing [at a time] in the House,” DeLay said.