What’s a conference committee, again?

Leaders on the House and Senate Appropriations committees are slated to meet in a real conference committee for the first time since 2009 next week after the Senate passes its “minibus” appropriations bill, as it is expected to do.

The plan is a victory for Senate negotiators who fought for the minibus approach, which combines three or four appropriations bills into a single package.

And it has the potential to revive a dead art on Capitol Hill. While they are the traditional staple of legislating, conference committees have by and large disappeared during the partisan battles of the past few years. Even when they have been used, many of them have essentially consisted of political theater to mask behind-the-scenes leadership negotiations.

But it’s only a trial. How smoothly it goes will shape how Congress tackles the rest of its appropriations bills.

If House and Senate negotiators iron out the differences of the two minibuses relatively easily, the rest of the appropriations bills could also be passed by minibus.

If the process bogs down, the impasse will give credence for wrapping up everything else in an omnibus.

“If and when the Senate passes that minibus they’re considering, hopefully Tuesday, we’ll immediately go to conference on those bills, those three. And then we’ll see what happens,” House Appropriations Chairman Hal Rogers (R-Ky.) said last week.

Leaders might attach a continuing resolution to the final product and could add as many as two other appropriations bills to the package.

The minibus approach, combined with a substantive conference committee, will blunt a push by House conservatives for an open rule on all appropriations bills through the end of the year.

“Conference reports are not amendable. That’s the rules of the House,” Rogers said.

Rogers can replicate the minibus-to-conference process for even the six appropriations bills not passed on the House floor, using the bills passed through the Appropriations Committee as the starting negotiating position for the GOP.

Republican Reps. Jeff Flake (Ariz.) and Mick Mulvaney (S.C.) said last week they were pessimistic about getting an open rule on any appropriations measures for the rest of this year.

“We haven’t gotten a full, solid commitment to it,” Mulvaney said in reference to a Flake-led letter to Speaker John Boehner (R-Ohio) pushing for transparency. “I think in this town, that means we’re not going to get it.” Conservatives say they’ll still push for openness, though, especially for bills that haven’t yet been to the House floor.

But even a closed or structured rule on the appropriations bills does not foreclose brinkmanship over policy riders.

For instance, the Interior and environment appropriations bill , passed through the Appropriations Committee but not the full House, includes 36 separate riders on environmental issues, mostly halting or stalling Environmental Protection Agency regulations.

An Appropriations Committee aide said one of those riders, which would weaken new regulations on mountaintop-removal mining, is a priority for Rogers. But protecting the regulation is also a priority for Democrats, who see a fight on the issue as a political winner.

House Minority Whip Steny Hoyer is circulating for signatures a letter to Boehner calling on Republicans to drop riders that are “not only controversial but blatantly partisan.”

The letter cites as examples provisions to strip funding for the new health care law, halt environmental regulations and alter laws on abortions.

But the letter doesn’t rule out all riders, saying “not all policy riders are objectionable.”

In a brief interview, the Maryland Democrat declined to say what riders Democrats might be open to, saying, “I don’t want to go into specific riders.”

But he described those that Democrats would fiercely oppose as “the usual riders that they put in that clearly are not out of the authorizing committee, clearly are very controversial, clearly will undermine the ability once again to reach agreement on funding the government in an orderly way so that we will give additional confidence to the country that we can operate in a bipartisan way to fund our government.”

House conservatives are also gearing up for the fight.

Rep. Steve King (R-Iowa) vowed last week not to vote for the Labor, Health and Human Services, and Education appropriations bill if it funds the health care law.

“I’m not funding” the health care law, he told Roll Call. King blasted Democratic officials for objecting to the use of the word “Obamacare” on taxpayer-funded Congressional mass mailings, calling it “outrageous.” He said he was looking for ways to again raise the profile of the law.

“I’m getting the sense that leadership may be poised to make some moves on Obamacare,” King added.

So regardless of how substantive the conference committee is, the coming showdown on riders is still on schedule. And the balancing act for GOP leaders remains the same. If they keep conservative riders, they scare away Democratic votes. If they jettison too many, they risk losing Republicans who are already upset over overall funding levels.