“Voting on the rule” may sound like nothing more than procedural inside baseball. But an enormous amount of policy and political consequence hinges on the fate of House roll calls on resolutions setting the terms for a bill’s consideration.

That’s as true this summer as it’s been in a long while. It’s not a stretch to say President Barack Obama’s top remaining second-term priority, and prospects for Republicans to prove competence at controlling Congress, both rest on this bit of the parliamentary process.

Last week’s crushing setback for the trade liberalization package was foreshadowed when 34 House Republicans broke ranks and voted against the rule. On Tuesday, the trade agenda was allowed to remain on life support only because there were just six GOP defectors on another rule.

And it’s very likely the legislation’s next climactic test will begin with yet another rule vote.

Even in an era when partisanship has become the default setting at the Capitol, the term “party discipline” sustains a negative connotation for many members. That’s because they market themselves back home as independent thinkers who won’t be pushed outside their ideological comfort zones by the bosses of their caucus.

Most Republicans have voted the opposite way from most Democrats at least 70 percent of the time in the past four years, a benchmark met just one other time in the past six decades. But that frequency of party unity has mainly been voluntary, a natural outgrowth of the GOP becoming more monolithically conservative and the Democrats more steadfastly liberal.

Political philosophy has been reliably checked at the door throughout the House’s modern history, however, when it’s come time to vote on the ground rules for considering legislation. On that front, blind loyalty to the leadership has been expected — and, to a very high degree, delivered.

Members of the majority understand their ability to pass the bills they want is significantly enhanced by their power to decide when those measures are brought to the floor and what amendments (if any) get considered. This pivotal traffic cop function is assigned to the Rules Committee, which is in essence an agent of the speaker. The plans the panel proposes are a manifestation of what the speaker believes is best for his majority.

So, in the current Congress, Republicans are expected to back the rule even when they oppose the underlying legislation, as both a recurring sign of support for Speaker John A. Boehner’s political sense and for preserving their control over the legislative process. And Democrats are expected to reflexively and consistently do the opposite: Vote against the rule, even when they like the bill, as a symbol of their disapproval of how the GOP is exercising its majority muscle.

It plays out that way with such remarkable consistency that the House last rejected a rules resolution almost 13 years ago. In the lame-duck session of 2002, anti-abortion advocates mustered the votes of an astonishing 87 Republicans (two-fifths of the conference) to defeat a rule that would have effectively completed a bankruptcy code overhaul championed by the financial services industry. (Abortion opponents opposed language that would have prevented “pro-life” protesters from filing for bankruptcy to avoid paying court-ordered fines.)

A repeat of that embarrassing defeat for the GOP high command got perilously close on June 11 on the rule setting up separate votes on the two interdependent halves of the trade package that’s already moved through the Senate. One part (Trade Promotion Authority) commits Congress to either accepting or rejecting, but not amending, whatever trade deal Obama completes with 11 other nations of the Pacific Rim. The other (Trade Adjustment Assistance) extends federal help for workers whose jobs are a casualty of more globalized commerce.

The vote was a whisper-close 217-212 because one in seven Republicans rebuffed the expectation of party discipline. The dissidents were on the cusp of bringing down the entire package until eight pro-trade Democrats also shirked their own party discipline and pushed the rule across the finish line.

The GOP dissenters, all from their conference’s most confrontationally conservative niche, mainly said they wanted to display disdain for the idea of giving Obama any authority to do anything. But for half of them, their ballot could also be fairly labeled as another vote of no confidence in the leadership. Of the 25 Republicans who voted in January against re-electing the speaker, 17 voted against the trade rule.

Boehner, who has had a famously long fuse after being crossed, signaled to his troops Tuesday that the limits to his patience had been reached on such procedural vote transgressions.

“I made it pretty clear to the members today I’m not very happy,” Boehner told reporters who asked him about the rule vote rebellion following a Republican Conference meeting focused on campaign fundraising strategy. “We’re a team and we’ve worked hard to get the majority, we’ve worked hard to stay in the majority and I expect our team to act like a team.”

The dressing down appeared to work, at least in the short run. A few hours later the House voted 236-189 to give GOP leaders and the White House six weeks to find a rescue plan for their shared trade aspirations. (The rule extends to July 30 the parliamentary deadline for reconsidering last week’s defeat of the TAA half of the trade bill.) Only six of the 23 GOP opponents of the first trade rule kept their disaffection going: Justin Amash of Michigan, Mo Brooks of Alabama, Louie Gohmert of Texas, Walter B. Jones of North Carolina, Thomas Massie of Kentucky and Bill Posey of Florida.

For the August recess to stand any chance of starting after the biggest bipartisan legislative achievement of the year, at least one more such display of procedural party discipline will be required.

Trade Votes of Past Point to Obama’s Troubles Ahead

GOP Leadership Mets Out Retribution for Rules Votes

The Democrats’ Ace by Night, Pivotal Trade Vote by Day

Tea Party Class More Confrontational Than Ever

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