If Senate Democrats assumed that getting 70 votes to advance an immigration-reform package would pressure House Republicans to vote on the Gang of Eight bill, they're going to be disappointed.

Knowledgeable Republican sources believe it's still possible for the GOP House and Democratic Senate to land in a conference committee negotiating a final immigration bill that could clear both chambers and garner President Obama's signature. But getting there is probably going to require Senate Democrats and the White House to accept the politics of immigration reform for House Republicans and what it would take for Speaker John Boehner to move such a bill.

"What they need to understand is that border security is the No. 1 issue," House Rules Committee Chairman Pete Sessions, R-Texas, said Tuesday during a brief interview. "The American people have to have confidence in what we do. Confidence means that we secure our border to make sure we're protected most of all."

In the aftermath of the 2012 elections, in which Hispanic voters overwhelmingly supported Democratic candidates, including 70 percent for Obama, Democrats saw a new political opening to push for immigration reform that includes a path to citizenship for illegal immigrants. And in fact, the Senate Gang of Eight immigration package would immediately legalize undocumented U.S. residents, although permanent residency is designed to be triggered only if the border is declared secure.

But despite years of negotiations toward a comprehensive bill by a bipartisan House working-group, don't expect the House to send to any conference committee the kind of vast rewrite of U.S. immigration law like the Senate's. House Republicans, in their safely gerrymandered districts, are hardly feeling heat from constituents to act. Immigration reform isn't hight on the list of priorities for Republican primary voters or voters overall.

However, that doesn't mean House Republicans aren't interested in immigration reform. Republican operatives with relationships in the House believe the path to a conference committee, and possible passage of a final compromise, is for the House to approve smaller border security and enforcement measures that have broad GOP support, and then meld those together with the path to citizenship that Democrats want and which the Senate included in its version of the bill.

An important caveat is that any bill must have the support of a majority of House Republicans. This element is considered crucial by a range of GOP sources, whatever their disagreements on how the immigration debate might play out. The Senate's "border surge" amendment, proposed by Sens. Bob Corker, R-Tenn., and John Hoeven, R-N.D., could prove instructive for Democrats wondering what might satisfy House Republicans on security.

House Republicans, however, would demand stronger triggers than were included in the Corker-Hoeven amendment to ensure that border security goes hand-in-hand with legalization and citizenship, sources say. "To pass and become law, it has to be something that congressmen would see as an asset to them if they had a tough primary race," a well-connected Republican consultant said.

"From looking at the survey research, it would seem that Corker's border surge would help but that it would also need a hard trigger to have a great chance in the House," the consultant added. "Most Republican primary voters can only consider a path to citizenship if they are certain it will have the integrity that comes with a secure border."

Last week, the House Judiciary Committee, which is driving immigration in the House, marked up two related bills -- one to improve interior security and another to create a guest worker program for farm laborers. This week, the panel is set to consider two additional bills, and more piecemeal legislation could be in the offing. But the path to a conference committee remains rocky.

House GOP leaders have yet to plot a legislative strategy, and called a closed-door July 10 meeting of their caucus to hear input. The potential complications Boehner is weighing, according to sources, include opponents of comprehensive immigration reform possibly voting "no" even on narrow bills they actually support just to block the House from entering into negotiations with the Senate.

Conservatives are genuinely divided on this issue -- including influential talk-radio hosts and outside groups. Even some Republicans who will never back comprehensive reform quietly hope legislation passes. And thus far, immigration reform proponents on the right have managed to speak just as loudly as the critics. But if that balance tips in favor of the opponents, the effort could derail completely.

"The politics of the GOP conference will make this a monumental challenge," a GOP lobbyist said.

david drucker Senior Congressional Correspondent