Congressional aides met all day Monday and will continue meeting this morning to try to reach a long-elusive compromise on extending wiretapping legislation that expires Aug. 3.

Negotiators aim to bring a bill to the floor later this week, breaking an impasse over retroactive immunity for telecommunications companies and other sticking points on legislation updating the 1978 Foreign Intelligence Surveillance Act.

To get a deal, the two sides still need to assuage the many egos involved in both chambers and stave off elements in each party that oppose compromising on the issue of immunity.

House Majority Leader Steny Hoyer (D-Md.) faces conservatives in his party who support full retroactive immunity and liberals who don’t want any immunity. And some Republicans have privately questioned why they are considering compromising now when the pressure will ramp up on Democrats when existing wiretapping rules expire in August.

Some immunity appears to be a certainty, but the question remains how broadly or narrowly it will be worded.

Aides to Hoyer and House Minority Whip Roy Blunt (R-Mo.) were leading the bipartisan, bicameral meetings.

Hoyer and Blunt agree “that there needs to be an agreement” sooner rather than later, a House GOP source said. “They’re the two that are saying, ‘Let’s make this happen.’”

Lawmakers have been tied up for months over FISA, namely on the issue of whether to grant retroactive immunity to telecommunications companies that aided the Bush administration in warrantless wiretapping after the Sept. 11, 2001, terrorist attacks.

Lawmakers are closing in on an agreement on immunity and court oversight of surveillance activities, sources said Monday night.

“We are still in negotiations, but any legislation produced will enhance the protection of constitutional rights for Americans and increase our nation’s security,” said Stacey Farnen Bernards, a Hoyer spokeswoman.

But Democrats are facing intense pressure from civil liberties groups and liberal activists who fear Democrats are poised to cave to White House demands.

Caroline Fredrickson, director of the Washington legislative office at the American Civil Liberties Union, complained that draft language circulated last week would effectively rubber-stamp the Bush administration’s warrantless wiretapping program.

Government officials could even bypass a court review of warrantless wiretapping procedures by citing “exigent circumstances,” such as time sensitivity, that they could argue would hurt surveillance, according to the ACLU.

“Because the government can rely on exigent circumstances as a way out, they won’t really need to go to court at all,” Fredrickson said. “This takes what the president has been doing — engaging in warrantless wiretapping — and puts the blessing of Congress on it.”

But a House Democratic aide said that Fredrickson was “100 percent wrong” and that the administration would have to go to court within seven days even under the “exigent circumstances” exception.

A House Democratic leadership aide also said the ACLU’s analysis was wrong and outdated.

“I would say that the ACLU has some key facts wrong; the ink isn’t dry on the deal and what we are working on will be a major improvement” on other bills and the existing law on civil liberties, the aide said.

Fredrickson also speculated that the Democrats might give in to White House demands on immunity so they can “capitulate early and take it off the table.”

An alternative would be to wait until August, when existing FISA authority expires, which would set up a politically perilous showdown in the middle of an election year.