It’s every Republican’s worst nightmare — waking up Nov. 5 to the horror of a House stocked with fresh new Democratic recruits to pad Speaker Nancy Pelosi’s (D-Calif.) control of the chamber and, even worse, a Senate under the control of 60-Member-strong Democratic majority.

Visions of a refreshed Senate Majority Leader Harry Reid (D-Nev.) unleashed to pass tax laws, health care bills and environmental overhauls would likely send most GOP faithful to Charlie Palmer’s — or window sills — for comfort.

Granted, it’s an unlikely scenario. The Senate has rarely seen a Majority Leader with a filibuster-proof majority, and while Democrats could make significant gains in the chamber this year, picking up nine or 10 seats is a long shot. Nevertheless, the prospects are intriguing, as are the changes that would result.

While Reid’s leadership team is expected to remain intact, top and mid-level policy aides could be expected to begin moving to K Street in droves to cash in on their newfound ability to pull levers in Washington, D.C.

One chairman, Sen. Joe Lieberman (ID-Conn.), could see his gavel imperiled at the Homeland Security and Governmental Affairs Committee.

While Reid has not threatened Lieberman with a loss of his chairmanship in retaliation for backing Sen. John McCain (R-Ariz.) in the presidential election, other top Democrats have openly warned that his future with their party is grim, and most on Capitol Hill say Lieberman’s chairmanship might not survive even a two- or three-vote pickup, let alone a 60-vote majority.

On the legislative front, the changes could, at least initially, be profound. One Democrat said Reid could be expected to push through dozens of small, relatively noncontroversial measures that have been caught in the partisan gridlock caused by the chamber’s 51-49 vote breakdown.

“There’s lots of little things that we all agree on” in the Democratic Conference, the aide said. Most agree gridlock would drop dramatically, and not simply because Reid could, in theory, break filibusters at will. Such a titanic shift in the chamber’s political makeup would likely be seen by many of the GOP’s survivors as a repudiation of their extensive use of filibusters and other stalling tactics over the past two years. With energy, health care and middle-class tax cuts expected to be at the top of Reid’s agenda — particularly if Sen. Barack Obama (D-Ill.) wins the presidential election — Reid could also find himself dealing with massive high-profile bills that have a chance of passing.

The expanded majority also could pose new problems for Reid. Take energy: Because of the razor-thin majority Democrats have held the past two years, the chances of major bills passing have been slim. That in turn has, to a certain degree, masked deep divisions within his party over how to address the issue, particularly between labor and old-line industrial interests and environmentalists.

But with GOP obstruction removed, these two factions would be freed up to re-create their fights of the 1980s and early ’90s. And Reid, as the Senate Democratic den mother, would find himself having to referee family fights rather than brawl with Republicans.

Republicans pondering a 60-vote Democratic majority say the biggest shift could be in Reid himself. Although he has long been known as a shrewd vote counter and floor tactician, the former boxer has always appeared most comfortable in combating Republicans.

But having to ride herd on a 60-vote majority — where Democrats could suddenly find themselves trying to break filibusters brought on by wayward Members rather than Republicans — could force Reid into the role of a mediator rather than pugilist.