At times it has become embroiled in controversy. In 2006, Reid apologized to 33 GOP senators after his communications shop issued a 27-page statement that accused lawmakers by name of ethical lapses. Republicans accused Reid’s shop of slinging mud in the clubby Senate.

But Republicans have also tried to imitate his tactics.

Six months after Reid established the war room, then-Senate Majority Leader Bill Frist (R-Tenn.) created a special task force to overhaul the party’s message strategy. In January of 2006, after a year in which many Republicans felt they had lost the communications battle with Reid, Frist launched a new communications center.

The Republican counterpunch has yet to match the war room. Senate Republican leadership aides say they have never built a messaging center as fully staffed as the war room.

“We don’t have anything approaching that,” said Don Stewart, communications director for Senate Minority Leader Mitch McConnell (R-Ky.).  

“We provide a robust, member-centric communications effort focused on helping Republican senators communicate our agenda, both nationally and in their home states,” said Stewart, who argued the Republican message center is less political. “This is an effort that includes radio, TV, print and new media.”

The rise of Senate war rooms has changed the Senate and fueled partisanship.

“I think the concept of Republican and Democrat war rooms changed the way the Senate functions by putting a focus on the communications effort,” said Bonjean.

Bonjean said the rise of partisanship in the Senate is mostly a reflection of the growing partisan divide in American politics. But the war room has added to the mix, he said.

“It does reinforce the partisanship, it can have the effect of reinforcing that partisanship,” he said.

Former Sen. Richard Bryan (D-Nev.), Reid’s home-state colleague, said the creation of the war room was a response to Republicans’ partisan maneuvers. Bryan cited Frist’s decision to travel to South Dakota to campaign against Daschle in his tightly contested race against now-Sen. John Thune (R), who ultimately triumphed.

A Senate leader had never before campaigned so openly against his counterpart.

“That broke all kinds of precedent,” said Bryan.  

“He was forced to become more aggressive,” said Bryan of Reid.

Bryan said that the Senate has become increasingly partisan in recent years.

“I regret it, because I think the institution has been damaged because of this increased lack of collegiality,” he said.

Bryan cited a Republican campaign ad in 2002 that juxtaposed former Sen. Max Cleland (D-Ga.), who lost three limbs in Vietnam, to Saddam Hussein and Osama bin Laden because he opposed a homeland security proposal that would have limited federal workers’ organizing rights.

Bryan, who left the Senate after the 2000 election, said that Reid has maintained good relations with Republicans even though some may object to some of his tactics as Democratic leader.

“Sen. Reid is a consummate insider and he has perfected the art of the deal,” said Bryan.