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.”