The bipartisan federal commission that probed the September 11, 2001 terrorist attacks is urging Congress to conclude its work on intelligence reform -- warning that the movement for reform could die if not acted upon this year.

The commission proposed a series of measures to reform the intelligence community with the aim of preventing another terrorist attack. The proposals included the establishment of a national intelligence director and the creation of a counterterrorism center to coordinate the gathering and sharing of intelligence.

The House and Senate adopted most of the commission's proposals in separate versions of reform legislation.

But negotiators for the two chambers have found it difficult to resolve differences between their respective bills.

Families of the victims of the September 11th attacks have called on President Bush to press lawmakers to reach agreement before Election Day, November 2nd.

Members of the September 11th Commission called a news conference on Capitol Hill Monday to urge Congress to redouble efforts to complete work on the legislation soon, if not this week, then in a so-called "lame duck" session after the elections.

Lee Hamilton, vice chairman of the Commission, said political momentum for intelligence reform will vanish once a new Congress is seated in January. "This is a real test of leadership. All of the work of the commission, and the very hard work of both houses of the Congress will die with the end of the (current session of) Congress, unless we act now," he said.

A key dispute between the House and Senate, both led by the Republican Party, involves how much power a new intelligence director would have over budget matters.

The Senate bill would give the director sweeping authority over budgets of the major Pentagon-based intelligence collection agencies.

But the House bill would continue to allow the Defense Department to control that power. House Republican leaders argue that shifting that authority to a national intelligence director could endanger the lives of soldiers in battle.

Senate negotiators argue otherwise, saying their proposal does not change the Defense Department's control over tactical intelligence assets.

House and Senate negotiators also are having difficulty resolving differences over House provisions concerning immigration and law-enforcement powers.

A White House spokesman says the president had asked Republican leaders in the House and Senate to work out differences and produce the legislation.