WASHINGTON — Senators filed out of a tense, closed-door session of the Senate Intelligence Committee this week, seemingly enveloped in an angry cloud of steam.
Sen. Pat Roberts (R-Kan.), the chairman of the panel, recalled the "nonpartisan tradition" of the committee. "We should fight the enemy; we should not fight each other," he said.
His Democratic counterpart, Sen. John D. Rockefeller IV of West Virginia, was fuming. A panel with one of the most sober assignments in Congress, he seethed, "is -- to put it bluntly -- basically under the control of the White House through its chairman."
Finger-pointing between Republicans and Democrats is hardly new behavior on Capitol Hill, where deafening exchanges across party lines are practically part of the legislative process. But the Senate Intelligence Committee had always been considered an oasis from the partisan bedlam, a preserve protected from such antics by the secretive nature of the agencies it oversees and the national security implications of its work.
Now many say that has changed, especially after committee members found themselves in the middle of a bruising political battle over President Bush's domestic spying program.
Tensions on the committee have escalated so sharply that the Senate's top Republican and Democrat traded accusatory letters in recent days, saying the toxic atmosphere threatened the committee's ability to function. Congressional experts and former members of the committee said they couldn't remember a time when the level of animosity on the panel was so extreme.
"I was on the committee for 10 years and I never experienced a situation similar to what appears to be going on now," said retired Sen. Bob Graham, a Florida Democrat, who was chairman of the panel during its investigation of intelligence failures surrounding the Sept. 11 attacks. "The extent of partisanship," he said, "is of a different order than I ever saw."
The strain erupted publicly this week after a showdown over whether the panel should investigate the espionage program authorized by Bush to monitor phone calls, e-mails and other communications of American residents without prior permission from a court.
But the friction has been growing for some time. Democrats and Republicans on the committee have clashed repeatedly in recent years over how the panel should respond to criticism of U.S. detention and interrogation tactics overseas, the leak of the identity of former CIA operative Valerie Plame, and the question of how the CIA and other agencies could have been so wrong about Iraq's weapons programs.
The committee was widely credited for producing a thorough report on those Iraq intelligence failures. But last year, both sides quickly sank into their most intense bout of partisan fighting over whether and how to complete the so-called phase two of that probe, which focuses on politicians using the intelligence claims to make the case for war. Portions of that project are said to be nearing completion after an extended delay.
Lawmakers and senior aides said that a number of factors have fueled the trend toward increased partisanship. Among them is the intensive public attention devoted to national security and intelligence issues in the wake of the Sept. 11 attacks.
"Everything we deal with now is so much more a national issue than it was before Sept. 11," said a senior Democratic aide on the committee who requested anonymity because of the sensitive nature of the subject. "We were thrust to the forefront of national politics."
As a result, the political stakes are significantly greater for members of the committee. Before the Sept. 11 attacks, the intelligence committees in the House and Senate captured the public's attention only intermittently -- typically when a spying scandal erupted, such as the arrest of Aldrich Ames in 1994, or when an intelligence failure occurred, such as the accidental U.S. bombing of the Chinese embassy in Belgrade in 1999.
Congressional officials also point to other factors. Some claim that the atmosphere in the Senate itself has coarsened over the last decade.
When asked about the origin of the partisan surge, Republicans often point to their discovery several years ago of a Democratic staff memo left on a copy machine in committee chambers. The memo outlined a strategy of trying to "pull the majority along" into inquiries that could embarrass the Bush administration.
Democrats resented the way Republicans publicized that memo, and point to other factors. They note that Roberts, the chairman, spent 16 years in the House of Representatives, where jousting between the parties is traditionally more intense than in the Senate. A spokeswoman for Roberts did not respond to a request for comment.