That could complicate the Senate’s plans to consider a bill approved by the Intelligence Committee last month that would grant retroactive immunity to the telephone companies that allegedly participated in the program after the 2001 terrorist attacks.

Dodd’s threats come as the Senate Judiciary Committee approved a bill Thursday to rewrite the 1978 Foreign Intelligence Surveillance Act. The bill, approved on a 10-9 party-line vote, has significant differences from the Intelligence Committee bill.

Most notably, the Judiciary bill is silent on the issue of retroactive immunity. The bill’s provisions would also sunset after four years, rather than the six-year requirement backed by the Intelligence Committee.

Senate Majority Leader Harry Reid (D-Nev.) said the Intelligence Committee bill will be brought to the floor in December, and the Judiciary Committee bill will be offered as a substitute amendment. Reid would not say which bill he supports, saying he still had to study the Judiciary measure, and he downplayed the differences between the two measures.

“But I think that we need to take a real close look at the immunity provisions,” Reid added. “They caused a lot of consternation within the conference.”

The White House and Republicans argue that those immunity protections are necessary to ensure companies are not unfairly penalized for helping the government on a national security program, and keep details of the secret program from being released during court proceedings. But Democrats and privacy advocates say that if the White House and the telecom firms were acting legally, immunity should not be granted.

The White House condemned the Judiciary Committee bill and promised a veto, but said Bush would sign the Intelligence Committee bill if it landed on his desk. The White House has also promised a veto on a House bill, which is silent on the immunity issue. Lawmakers approved that bill 227-189 Thursday night.

The Senate Judiciary Committee’s bill is all but certain to face strong GOP opposition on the floor.

Intelligence Vice Chairman Kit Bond (R-Mo.) said in a statement late Thursday that the new bill “would gut our critical terrorist early warning system.” He called the Senate version, which passed on a largely bipartisan vote in October, “the only bill that will protect American civil liberties without handcuffing our terror-fighters.

Similarly, Intelligence Committee Chairman Jay Rockefeller (D-W.Va.) told reporters Friday he would defend his panel’s bill on the floor and signaled he would oppose amendments aimed at watering down the immunity provision.

But a host of powerful figures in the Democratic Conference are opposed to Rockefeller’s bill, including Sen. Patrick Leahy (Vt.), chairman of the Judiciary Committee.

“Passing a law to whitewash the administration’s undermining of another law would be a disservice to the American people and to the rule of law,” Leahy said.