House Republicans will meet Wednesday to hash out their differences on immigration legislation, and there is a lot of hashing out to be done. The session is expected to last hours, and, if recent history is any guide, a lot of it is likely to be contentious and unpleasant.

Since the 2012 election, the House GOP conference has proved to be as fractious and unwieldy as any in recent memory, with members openly antagonizing the leadership on a number of key issues, including the “fiscal cliff,” the reelection of Rep. John A. Boehner (R-Ohio) as speaker and, most recently, a failed federal farm bill. A Senate version of the farm bill passed with a solidly bipartisan 66 votes.

It is against this backdrop that House GOP leaders try to begin mapping a way forward for a difficult immigration overhaul effort, hoping that this time they can corral enough support from each of the various GOP factions at the end of what promises to be a long and complex process.

A review of recent legislative battles shows that will not be an easy task. The six votes that have proved most divisive for the GOP conference since the November election — on the fiscal cliff, Hurricane Sandy relief, the debt limit, the Violence Against Women Act, the farm bill and the selection of a speaker — each seemed to leave Boehner and his team in a weaker position for the next round of battle. And immigration may be the toughest test yet for Republicans, who will be grappling with difficult questions about border security and a pathway to citizenship for illegal immigrants.

All told, 69 of 234 House Republicans (nearly 30 percent) have voted against leadership on at least half of the six key votes, and a majority — 134 out of 234— has departed from the leadership on at least two of the six votes, according to the Washington Post review.

See the Republican factions in the House

The six key votes are not a perfect predictor of how members will vote on immigration, but they show how little emphasis members place on party unity these days. GOP leaders cite a number of causes for this, including conservative groups and voices playing an increasing role in Republican primaries and the loss of earmarks and other bargaining chips they once used to corral votes.

Each of the past votes carried its own complicating factors that discount the idea that members are simply determined to buck leadership. On the fiscal-cliff vote, for example, GOP leaders were split. And on the farm bill, a majority of Democrats voted against something that typically has huge bipartisan support. Without those Democratic defections, the farm bill was likely to pass despite the muted GOP support.

But the overall picture is one of a House GOP conference that is highly factionalized and diffuse, with members having little in common. And few are afraid to flout the leadership, with just 46 members voting with leaders on all six measures. During the farm bill vote, six party chairmen — whose fealty to leadership was once a given — joined with 56 other Republicans to vote no.

“The takeaway is that John Boehner has the worst job in politics. I’m not sure Jefferson could get 218 votes in our conference,” said Rep. Trey Gowdy (R-S.C.), referring to the number of votes needed to pass a bill in the 435-member House.

Immigration will come into focus Wednesday when House Republicans meet in a special, closed-door conference. The open-mike-style gathering will offer leaders a chance to take the collective temperature of Republicans on immigration and allow rank-and-file members to voice their preferences and concerns.

“That meeting is very important,” said Rep. Bob Goodlatte (R-Va.), the chairman of the House Judiciary Committee, which has approved four immigration bills. “It will allow the members to express their views on what immigration reform bills they can support.”

The Senate recently passed a sweeping immigration bill that beefs up border security and offers a path to citizenship, but House GOP leaders have balked at bringing it to a vote. It earned only about one-third of Republican votes in the Senate, and it would need the support of half of House Republicans to even go to a vote, according to the rules agreed to by Boehner.

To some House Republicans, the debate is slowing down, not speeding up, now that it is the lower chamber’s turn to act.

“Unlike, again, fiscal cliff or sequester,” said Rep. Tom Cole (R-Okla.), “there’s no hard and fast deadline here.”

To others, the conference needs to sort out where it stands on arguably the most contentious issue in the debate: a pathway to citizenship that many reform advocates say is a must-have.

“I think we really need to separate our conference down to, ‘Do you support a path to citizenship, or don’t you?’ And if their answer to that is yes in the majority, we’ve got a major problem,” said Rep. Steve King (R-Iowa), perhaps the chief immigration hard-liner in the House.

The Senate bill includes a 13-year path toward permanent residency status or citizenship for illegal immigrants and would require them to pay thousands of dollars in fines and back taxes. Senate Republicans pushed for stricter border security elements before they would agree to support the larger bill. But even with the addition of a “border surge” negotiated by two GOP senators, 32 of 46 Republicans voted against the overall package.

In the House, none of the five immigration bills that have advanced out of committee include a pathway to citizenship, illustrating a stark difference in priorities between the two chambers. The House bills deal mainly with border security, law enforcement and employment issues.

Goodlatte said he does “not believe that we should give a special pathway to citizenship to people who entered the country illegally.” But, the Republican said, he is open to the idea of a special legal status for children brought into the country illegally at an early age.

House Majority Leader Eric Cantor (R-Va.) signaled last week that the chamber may be ready to begin considering the narrower proposals that have advanced from committees. But one question that has yet to be settled is whether a bipartisan “Group of Seven” proposal from members of Congress, one that is likely to contain a new path to citizenship, can attract substantial support from House Republicans.

“We have a final proposal,” said Rep. Mario Diaz-Balart (R-Fla.), one of the group’s members. He added, “We’re just now going through it to make sure that everything we have agreed to is actually reflected in the final draft.”

Complicating matters further, external forces are applying pressure on House Republicans to pass a comprehensive bill. The Service Employees International Union announced Monday that it would air Spanish-language ads in 10 GOP districts urging support for a path to citizenship. And the conservative American Action Network began a modest ad campaign touting the Senate bill.

But those calls are unlikely to be heeded in many Republican districts, where the threat of a primary looms much larger than a Democratic opponent in the general election. And being perceived as soft on immigration could invite challengers on the right.

“You would expect members to respond to their pressure points,” said Tom Davis, a former National Republican Congressional Committee chairman. “It’s not the middle of the road, and it’s not party leaders.”