WASHINGTON – House and Senate leaders are signaling that they may face insurmountable obstacles in their bid to overhaul the nation’s intelligence community before the elections.

Senate Majority Leader Frist of Tennessee has begun to talk in terms of passing legislation before the end of the year instead of before November 2. Some congressmen say privately that reform may not be achievable until next year and question the chances of passing significant legislation during a lameduck session following the election.

The biggest difficulties are coming in the Senate, where Mr. Frist has yet to shape a strategy to cope with expected contentious amendments to the leadership-endorsed bill co-authored by Senator Collins, a Republican of Maine, and Senator Lieberman, a Democrat of Connecticut. “I don’t know what is going to happen on the floor of the Senate,” Mr. Frist said to reporters.

Because of splits within both parties, Mr. Frist will not be able to rely on his deputies to back him in defeating amendments seeking to weaken the powers of the new national intelligence director or amendments aiming to boost the director’s role beyond what the Collins-Lieberman bill proposes.

Senators on the Armed Services Committee want the new director’s authority to be reduced and want to weaken the reach of the proposed National Counterterrorism Center. While members of the Senate Intelligence Committee maintain that the director needs greater budgetary authority to have control over non-military agencies.

The 9/11 commission, which found major intelligence failures leading up to the terror attacks on New York and Washington, recommended the appointment of a new powerful director and wanted the post holder to oversee the entire intelligence community. Both the Senate and the House reform bills diverge from the 9/11 commission by leaving control of the military intelligence agencies and the Defense Intelligence Agency in the hands of the Pentagon.

Furthermore, the House and Senate bills are very different, with the House proposals envisaging a much weaker new intelligence director with even less budgetary authority. The Senate started debate on the Collins-Lieberman bill this week, and Mr. Frist hopes floor action on the bill will be completed by the end of the week.

In the House, half-a-dozen committees are currently marking up a broader reform bill than the Senate’s. The House bill, which includes substantial law-enforcement and immigrations provisions, won’t reach the floor until next week, leaving a handful of days before Congress recesses on October 8.

House Speaker Hastert of Illinois has indicated he would be ready to recall Congress for a Halloween session to vote on the result of a conference working out the differences between the bills.

But a conference is likely to prove every bit as hard as securing passage in the Senate of the Collins-Lieberman bill. Mr. Lieberman has criticized the House bill for not giving the national intelligence director’s position “the strength it needs to run the intelligence community.”

While endorsing the bill the White House budget office said it was “concerned about the excessive and unnecessary detail” contained in it.