The procedural fits Republicans have caused Senate Majority Leader Harry Reid (D-Nev.) on the health care bill are just the latest sign of an increasingly aggressive GOP Conference that has used unity and discipline to stymie Democrats’ legislative agenda for much of the year.

But over the weekend, as the Senate took a major step toward passage of health care reform legislation, Democrats appeared to be using Minority Leader Mitch McConnell’s (R-Ky.) tactics against him, as a rallying point for the majority.

“It’s like they’ve gone too far,— Finance Chairman Max Baucus (D-Mont.) said Saturday, noting that in the last several days Democrats have grown more united in their desire to reach some sort of deal. “I think it has [helped]. They’ve energized the troops,— Baucus said

On virtually every major legislative item that Reid has tried to move this year — including the stimulus package, the auto industry bailout, the omnibus spending bill, defense spending and health care — Republicans have overcome their sparse numbers to wield significant power in the chamber.

The Republicans have repeatedly drawn Reid into long procedural fights and in many cases forced him to move less-than-ideal legislation on hard-won, party-line votes. And with rare exceptions — including the nomination of Supreme Court Justice Sonia Sotomayor — Republicans have marched in lockstep.

The level of the GOP’s success — and the lengths to which Republicans will go in their war with Reid — is surprising given the position they were in in January.

As President Barack Obama was inaugurated, the year looked bleak for McConnell and his colleagues: They had suffered their second straight electoral defeat, they had lost the bully pulpit of the presidency, Reid seemed increasingly likely to gain his 60-vote majority and the GOP was in the midst of ugly internal recriminations.

Hoping to overcome those odds, McConnell and his leadership team have consistently drilled into the Conference that for Republicans to have any influence in the Senate — or any chance of returning to power — they must work as a unified group and demonstrate message discipline, Republicans said.

“I give our leadership, Sen. McConnell and [Minority Whip Jon] Kyl [Ariz.], a lot of credit,— National Republican Senatorial Committee Chairman John Cornyn (Texas) said Friday. “We’ve been more unified than I ever believed possible.—

Democrats acknowledged Republicans have had success at Reid’s expense. “It’s become something of an obsession,— Sen. Jack Reed (D-R.I.) said Friday, arguing that Republicans are following “essentially a program of ‘just say no’— and that any policy proposals they do make are “just peripheral to what they’re up to.—

McConnell’s first taste of success came with the stimulus bill, when he persuaded his colleagues to remain largely unified in opposition to Democrats’ plans. In doing so, McConnell forced “Reid to get all of his people on board— the bill in order to pass it, a move that allowed Republicans to cast the legislation as a partisan expansion of the government’s debt.

So long as Reid could count on peeling off a stray moderate Republican or two, or in the case of the Defense spending bill, notoriously loyal appropriators, he could always afford to lose one or more of his own moderates.

But by taking his Conference out of the negotiating process on the stimulus and other bills, McConnell ultimately undercut the power of Reid’s 60-vote majority.

With Republican votes suddenly off the table, Reid was forced to find votes within his own Conference, and the long-standing divisions within the Democratic Party have become increasingly pronounced as a result.

Moderates like Sens. Ben Nelson (D-Neb.) and Joe Lieberman (ID-Conn.) found themselves with new leverage over Reid. As the partisan tone has increased, both sides have become increasingly content with legislation passing on party-line votes — and Reid’s margin of error has become nearly nonexistent.

With the exception of Sen. Olympia Snowe (R-Maine), none of the Senate’s other 39 Republicans have shown any willingness to work with Democrats on the health care reform package, forcing Reid to find a way to keep his Conference together — a balancing act that he is still struggling to perfect.

McConnell and his colleagues have also become increasingly comfortable in using cloture motions and other tactics to slow down legislation — even if their own approval ratings have not improved. Republicans have used those tactics to block legislation like unemployment insurance and force weekend votes on the omnibus bill and health care.

The GOP went so far as to use the Defense spending bill as a stumbling block in its fight against Reid — a notion that seemed unthinkable for the “national security— party.

Democrats bemoaned Republicans’ tactics, accusing the GOP of fundamentally undermining the chamber.

Republicans are “undermin[ing] the essence of why we are here,— Sen. Mark Begich (D-Alaska) charged on Friday, arguing that GOP Senators, “by their actions and now delay tactics, they’re setting the schedule.—