There's a fundamental conflict at the heart of the Senate debate over the Gang of Eight comprehensive immigration reform bill. Most Republicans believe a policy to integrate 11 million currently illegal immigrants into American society must be conditioned on stronger border security and internal enforcement. Most Democrats don't. At bottom, that's what the fight is about.

Most Republicans believe security must come before integration, in one of two ways. Some believe enhanced security must be in place -- not a plan, but a reality -- before the 11 million can be granted temporary legal status. (In the world of the Senate, "temporary" means six to 10 years.) It's probably fair to say that a majority of the Republican voting base holds that opinion.

Other Republicans believe enhanced security must be in place -- again, reality, not a plan -- before the legalized immigrants can move on, after 10 years, to permanent legal resident status, signified by a green card, and ultimately on to citizenship.

What unites the two camps is the conviction that enhanced security must actually be in place before today's illegal immigrants are allowed to stay in the U.S. for the rest of their lives.

Many Democrats pay lip service to the idea; after all, it's pretty popular not just with Republican voters but with Democrats and independents, too. But they don't see enhanced security as something that has to happen before immigrants may move forward.

If there were any doubts that many Democrats do not support enforcement before integration, those doubts were dispelled this week by Sen. Richard Durbin, a leading Democrat on the Gang of Eight. "We have de-linked a pathway to citizenship and border enforcement," Durbin told National Journal. And Sen. Charles Schumer, another leading Democrat in the Gang, calls a recent Republican attempt to strengthen the link between enforcement and the path to citizenship "a nonstarter."

As Democrats see it, reform must move today's illegal immigrants to temporary legal status, and then to permanent legal status, and then to citizenship without any major obstacles along the way. A requirement that any of those steps be dependent on specific security and enforcement improvements is a nonstarter not just for Schumer but for Senate Majority Leader Harry Reid and most other Democrats.

Right now, Durbin, Schumer and Reid have the advantage. The Gang of Eight bill being debated in the Senate does not require any security advances before illegal immigrants are granted a decade-long "temporary" legal status. And all that is required before those same immigrants move on to permanent legal status and citizenship is that a "Comprehensive Southern Border Security Strategy" be "substantially deployed and substantially operational."

What does "substantially" mean? It could mean anything, which is why lawmakers who don't want to place specific security requirements before permanent legalization like it.

When Sen. John Cornyn proposed to take out the word "substantially" and replace it with the specific standards for border security -- 100 percent surveillance of the border, a 90 percent apprehension rate -- Democrats immediately rejected it. They vowed never to even negotiate the issue.

Both Democrats and Republicans have been happy to let the public think the bill is tougher than it is. For example, Sen. Marco Rubio, the leading Republican on the Gang of Eight, talks all the time about the importance of putting new security measures in place, but he means before immigrants are given permanent status, not before the temporary, decade-long legalization that starts the process.

Rubio made that crystal clear in a recent Spanish-language interview. "First comes the legalization," he told the network Univision. "Then come the measures to secure the border." He added that legalization "is not conditional" -- that is, it doesn't depend on any new security measures being in place.

A number of Republicans were surprised by Rubio's words. When he talked about enhanced security these last few months, they thought he meant security before the first round of legalization. He didn't.

And just to make it unavoidably clear, on Thursday the Senate voted on an amendment proposed by Republican Sen. Charles Grassley that would have delayed the first, "temporary" legalization until six months after border security was actually in place. Rubio voted against it, along with the rest of the Gang of Eight and nearly every Democrat.

And even when it comes to the granting of permanent legal status, the Gang bill requires "substantial" deployment of new security, whatever that is. There's simply no requirement that the border be definitely, measurably secure before today's immigrants complete the journey from illegality to citizenship.

That's the way the Gang of Eight wants it.

Byron York, The Washington Examiner's chief political correspondent, can be contacted at byork@washingtonexaminer.com. His column appears on Tuesday and Friday, and his stories and blogposts appear on washingtonexaminer.com.