Sen. Hillary Rodham Clinton (D-N.Y.) was the original impetus behind the Senate Democratic “war room,” a legacy the candidate does not mention on the campaign trail but one that has significantly changed the upper chamber.

The war room is the name for the communications center that Senate Majority Leader Harry Reid (D-Nev.) created after the disastrous 2004 election, when Democrats lost four Senate seats, including the seat held by former Democratic leader Tom Daschle (S.D.).

Clinton was one of the first and most forceful advocates of establishing a campaign-style communications center in the Senate. Her husband, former President Bill Clinton, pioneered the use of a rapid-response campaign center during his successful 1992 run, chronicled in the 1993 D.A. Pennebaker documentary “The War Room.”

Clinton first proposed a Senate war room while Daschle was the Senate Democratic leader, but the soft-spoken South Dakotan declined to implement her idea, said Ross K. Baker, a political science professor at Rutgers University who on Friday finished a five-month stint as a guest observer working in Reid’s leadership office.

Daschle did not respond to several requests for comment.

Creating a campaign-like war room was controversial. Daschle created special communications operations to push specific bills, such as the patients’ bill of rights, but stopped short of establishing a permanent war room.

Reid, however, embraced the idea immediately after Clinton suggested it to him during his campaign for Democratic leader in November 2004.

Some Democrats, such as Sens. Ron Wyden (Ore.) and Jack Reed (R.I.), asked for committee assignments when Reid called to solicit support for his leadership race.

Reid recounts the experience in his new book, “The Good Fight.”

“Hillary Clinton, who is as tough and smart as any senator I’ve seen, told me that we needed to establish a ‘War Room’ to combat the Republican noise machine and take our message to the country.

No more Swift Boats,” Reid writes in reference to a Republican-allied political advocacy group that damaged the 2004 Democratic presidential nominee, Sen. John Kerry (Mass.), with harsh political attacks. “This was excellent advice born of hard experience.

“We would act on Hillary’s suggestion quickly,” Reid writes.

Many Democrats felt like the war room was needed after the 2004 elections, claiming Democrats were not as tough as Republicans. Reid, a former boxer, wanted to make sure that when Republicans attacked, Democrats would counter.

In her run for the White House, Clinton has noted that she has battle scars from her political fights with Republicans. But she has mostly touted her bipartisan work in the Senate, claiming that she could bring the parties together.

Jim Manley, Reid’s senior communications adviser, said the war room was chiefly Reid’s creation.

“She [Clinton] had been pushing for a war room but it was Sen. Reid’s idea,” said Manley, who oversees the war room. “She was a proponent of it, but in the end it was Sen. Reid’s idea.

“He recognized there was a rapidly changing media environment and he needed a communications center that would deal with all forms of media, including online media and outreach to Hispanic media,” said Manley.

Clinton’s spokesman referred a query to Reid’s office.

The war room that Reid established after the 2004 election eventually swelled into an operation staffed by 25 to 30 aides.