"On day one of our bill, the people without status who are not criminals or security risks will be able to live and work here legally."

With those words, Democratic Sen. Charles Schumer, who moments earlier had heaped effusive praise on Republican colleagues standing with him in the Senate press room, made it infinitely more difficult for many GOP lawmakers to sign on to the bipartisan immigration proposal put forward by the so-called Gang of Eight.

The problem is that giving instant legality -- it's now called "probationary legal status" -- clashes with the principle, deeply held among many conservatives and Republicans, that securing the border must come before creating a mechanism for legality and, ultimately, a path to citizenship for the roughly 11 million illegal immigrants already here.

Sen. John McCain, standing at Schumer's side, surely knows that. Back in 2007, as he ran for the Republican nomination for president, McCain ran into a torrent of opposition in the early caucus and primary states.

GOP voters didn't buy a "comprehensive" solution to illegal immigration. They wanted to see the border secured first. When a politician proposed to grant what critics called "amnesty," and also secure the border at the same time, the skeptics believed the "amnesty" would happen but the security would not.

"What I underestimated was the lack of trust and confidence in government," McCain said in November 2007. "I mean, I said time after time, 'We'll enforce the borders. We'll enforce the borders. Here's X billion dollars to do it. We'll enforce the borders.' They just didn't believe us."

So this time, Republicans, led by McCain and Sen. Marco Rubio, have insisted on provisions they claim will ensure the new system will be tough. "Individuals with probationary legal status will be required to go to the back of the line of prospective immigrants, pass an additional background check, pay taxes, learn English and civics, demonstrate a history of work in the United States, and current employment, among other requirements, in order to earn the opportunity to apply for lawful permanent residency," says the five-page bipartisan proposal.

But the bottom line is, those who are here illegally now, unless they have some sort of serious criminal record, will be made legal on the first day the new law takes effect. So wouldn't day-one legality be an incentive for more people to come to the U.S. illegally?

"One of the details that has yet to be worked out is how long you have to be in the country before you can qualify for the temporary legal status, but it will probably be a couple of years," says one Senate source. "So people who came illegally yesterday, or next week, won't qualify. They will have to leave the country."

When asked whether that would mean everyone who came to the U.S. illegally in the two years prior to the law's going into effect would be deported -- a very heavy lift politically -- the source answered, "We need to figure out the details, but we don't want to encourage a race to the border, obviously."

And there are more details. The bipartisan group is touting a new commission that would determine whether the border is in fact secure. But the new proposal says only that the commission will make a "recommendation" on that. The same Congress that has been deeply divided over border security for years would ultimately make such a determination, which again might not inspire confidence among many conservatives and Republicans.

At this early moment, there are plenty of doubts to go around. In a floor speech shortly after the bipartisan group introduced its plan, Republican Sen. Jeff Sessions recalled the days in 2006 and 2007, when another bipartisan group came up with another immigration plan. "We were all supposed to line up and vote for it," Sessions said. "The Masters of the Universe had decided ... But the American people said no."

Other GOP senators are equally skeptical, at least for now; don't look for many to jump on board. "There's no reason to embrace a five-page, notional product now, when the Judiciary Committee will almost certainly pull it farther to the left," says another Senate Republican aide. "Everybody on our side wants Rubio to succeed, but I think a lot of members will think it imprudent to sign off on this so quickly."

The conventional wisdom holds that Washington will take action on immigration reform this year. But it will be a hard, hard fight.

Byron York, The 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.