Senate Democrats and Republicans have increasingly sought to use the chamber’s complex and arcane rules to their advantage, turning the “cooling saucer” of the legislative branch into the scene of often bitter, guerrilla-style tactical fights.

Whether it has been Republicans using minor drafting errors to derail portions of the health care reconciliation bill or Democrats stretching an obscure precedent to short-circuit GOP efforts to stall health care legislation last year, both parties have placed greater emphasis on the chamber’s rules over the past year and a half.

“I do think it’s true that the rules have been used with greater vigor lately,” a GOP aide involved in mining the Senate rules for tactical advantages said.

Republicans largely see it as a positive outgrowth of the migration of House Members into the Senate, but Democrats say it has heightened partisanship and slowed the chamber’s already snail’s pace of legislating.

“It’s just an indication of how partisan the chamber has become. We used to be able to get unanimous consent on motions to proceed,” a former Democratic floor operative said, arguing that because of the partisan atmosphere “both sides look for ways to use the rules to advance their agenda.”

At the core of this new emphasis on the rules, current and former aides said, is the growing number of Senators who served previously in the House.

Tom Coburn (R-Okla.), Jim DeMint (R-S.C.), Sherrod Brown (D-Ohio) and Bernie Sanders (I-Vt.) are among those who have made the jump from the House to the Senate in recent years, leaving behind the restrictive nature of the House for the Senate’s more open atmosphere.

“As the character and characters of the Senate evolve, Members are digging deep into the rules … to understand how the Senate works and how to make things work to their advantage,” said Eric Ueland, who worked as former Majority Leader Bill Frist’s (R-Tenn.) chief of staff.

Compared with the House, where the Rules Committee largely dictates how legislation is considered, individuals in the Senate enjoy a high degree of flexibility. “In the Senate, you have a lot of opportunity and everyone can to some extent be an independent operator. … That’s invigorating for Members,” Ueland said.

Coburn spokesman John Hart agreed, noting that while Coburn found creative ways in the House to make his concerns known — most notably by offering 130 amendments to an agriculture spending bill a decade ago to create a de facto filibuster — he “entered the Senate very eager to have that same effect without having to offer 130 amendments.”

“Dr. Coburn believes he has the constitutional right to ensure the views of taxpayers are heard, and if those views are being ignored, he believes the Senate rules give him the right to make sure they are heard,” Hart said.

“He tries to use the rules most aggressively when he believes he has the support of the American people,” Hart said, adding that while Democrats view him as an obstructionist, “the rules to him are a spotlight, not a roadblock.”

Indeed, Coburn has been the author of some of the GOP’s best procedural hits — most recently forcing the Senate clerk to read a 767-page amendment to the health care bill in December.

Members have rarely forced full bills or lengthy amendments to be read, but Republicans, led by Coburn, decided to invoke the rule, hoping not only to slow down work on the bill but to also create a platform from which to make their case on the legislation to a national audience. Forcing the reading of an amendment had up until December been viewed as something of a rarely used trump card, since there was no known way to force an end to the reading without Coburn’s agreement.

But while the gambit did draw significant media attention, it also underscored the willingness of Democrats to use the rules creatively as well.

After several hours of reading, Majority Leader Harry Reid (D-Nev.) — one of the chamber’s masters of procedure — unearthed an obscure ruling from the mid-1990s that would allow Sanders, the amendment’s author, to withdraw the amendment and thus end the reading.

Additionally, Sanders, Brown and other freshman and sophomore Democrats have pressed Reid and other Democratic leaders in recent months to use the rules to bring an end to Republican holds and other stalling tactics.

That strategy was on full display in February when freshman and sophomore Democratic Senators, led by Majority Whip Dick Durbin (D-Ill.), forced Sen. Jim Bunning (R-Ky.) into actually filibustering their attempts to pass an unemployment insurance bill rather than allowing him to use a hold to block it.

Ueland and others maintain that the increasing use of the Senate’s rules — along with the efforts of the chamber’s junior Members to find new and creative means to make their presence felt — is ultimately a good thing and will likely continue.

“My guess is, this will continue to flower … as you watch more and more House Members coming to the Senate,” Ueland said.

Rodell Mollineau, a spokesman for Reid, agreed that the recent crop of former House Members has had a significant effect, but he took a decidedly dimmer view of the implications for the Senate.

Mollineau argued the shift to a more tactical style, as opposed to the chamber’s traditional emphasis on congeniality, has been driven by Republicans who first came to Washington, D.C., as Members of the House in the mid-1990s.

“There are members of the Republican caucus that came to power during the so-called Republican Revolution when their leaders promoted hyper-partisanship and taking down a Democratic president,” Mollineau said.

“Unfortunately, that mindset has carried over from their time in the House to the Senate,” Mollineau added.

Also, Mollineau argued that since none of the former Republican House Members were in the minority in the House — which given the chamber’s rules can be a lonely position for those not inclined to bipartisanship — their first instinct has been to fight rather than seek cooperation when faced with a Democratic majority.

Former House Republicans in the Senate have “reacted rather harshly to finding themselves in the minority and having to seek cooperation while in the Senate,” Mollineau said.

A former top GOP strategist, however, dismissed Democratic complaints about partisanship, pointing out that Reid has made use of the rules both publicly — as in the case of the fight with Coburn in December — and more quietly, most notably when he spent hours working with Senate Parliamentarian Alan Frumin in efforts to write a reconciliation bill immune from procedural challenges.

“They spent weeks locked in a closet with the Parliamentarian trying to come up with a bill the House and Senate could agree on on substance and on process wouldn’t have to be voted on again,” this former aide said.

A current Republican aide agreed, arguing that it is a simple fact of life in the Senate that virtually any Member of either party can, if they are so inclined, use the rules to essentially hijack the chamber.

“Anyone who wants to exercise their rights can be a de facto Majority Leader,” this aide said.