Senate Majority Leader Sen. Harry Reid (D-Nev.) speaks to the media Tuesday on Capitol Hil. (Manuel Balce Ceneta/AP)

The Senate is on the verge of striking down the long-standing filibuster rules for most presidential nominations, potentially doing so on a party-line vote that would alter nearly 225 years of precedent.

Democrats, infuriated by what they see as a pattern of obstruction and delay over President Obama’s nominees, expect to trigger the showdown by bringing up one of the recent judicial nominees whom Republicans blocked by a filibuster. According to senior Democratic aides, Majority Leader Harry M. Reid (D-Nev.) will set in motion a complicated parliamentary process that ends with a simple-majority vote setting a new rule that will allow for swift confirmation of executive branch nominees and most selections for the federal judiciary without having to clear a 60-vote hurdle.

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If Democrats go through with the threat, it will allow for confirmation of several nominees to the U.S. Court of Appeals for the D.C. Circuit who have recently been stymied by GOP filibusters, amid Republican assertions that the critical appellate court simply did not need any more judges.

The impact of the move is more far-reaching, however. The means for executing this rules change — a simple-majority vote, rather than the long-standing two-thirds majority required to change the chamber’s standing rules — is more controversial than the actual move itself.

Many Senate majorities have thought about using this technical maneuver to get around centuries of parliamentary precedent, but none has done so in a unilateral move. This marks at least the fourth time in three years that Reid has rattled his saber on the filibuster rules, each time yielding to a bipartisan compromise brokered by the chamber’s elder statesmen.

As of Wednesday night, no bipartisan talks had emerged. Sen. John McCain (R-Ariz.), the main negotiator who brokered recent deals to avert such a showdown, as well as one in 2005, met with Reid on Wednesday, but neither side reported progress.

The main protagonists for the rules change have been junior Democrats elected in the last six or seven years, who have alleged that Republicans have used the arcane filibuster rules to create a procedural logjam that has left the Senate deadlocked. Upon arriving in 2009, Sen. Tom Udall (D-N.M.) said, he found that “the Senate was a graveyard for good ideas.”

As he recounted in a speech this week, Udall said, “I am sorry to say that little has changed. The digging continues.”

As envisioned earlier this week, Democrats would issue a new rule that would still allow for 60-vote-threshold filibusters on legislation and nominees to the Supreme Court.

Republicans, weary from the third rules fight this year, seemed to have adopted a resigned indifference to this latest threat, as opposed to the heated rhetoric in mid-July when the issue last flared up. Sen. Charles E. Grassley (R-Iowa), the ranking Republican on the Judiciary Committee, mocked the idea that the Democrats would leave in place the filibuster rule for Supreme Court nominations, in the event that a GOP nominee wins the White House in 2016.

He made clear that if that occurred, and the GOP reclaimed the Senate majority, the Republicans would then alter the rules so that Democrats could not filibuster a Republican pick for the Supreme Court. “If [Reid] changes the rules for some judicial nominees, he is effectively changing them for all judicial nominees, including the Supreme Court,” Grassley said Wednesday.

Reid’s move is a reversal of his position in 2005, when he was minority leader and fought the GOP majority’s bid to change rules on a party-line vote. A bipartisan, rump caucus led by McCain defused that effort.

At the time, Sen. Mitch McConnell (R-Ky.) was the No. 2 GOP leader and helped push the effort to eliminate filibusters on the George W. Bush White House’s judicial selections. Eight years later, McConnell, now the minority leader, has grown publicly furious over Reid’s threats to use the same maneuver.

Democrats contend that this GOP minority, with a handful of senators elected as tea party heroes, has overrun McConnell’s institutional inclinations and served as a procedural roadblock on most rudimentary things. According to the Congressional Research Service, from 1967 through 2012, majority leaders had to file motions to try to break a filibuster of a judicial nominee 67 times — and 31 of those, more than 46 percent — occurred in the last five years of an Obama White House and Democratic majority.

Republicans contend that their aggressive posture is merely a natural growth from a decades-long war over the federal judiciary, noting that what prompted the 2005 rules showdown were at least 10 filibusters of GOP judicial nominees. To date, only a handful of Obama’s judicial selections have gone to a vote and been filibustered by the minority.