You guys are not seeing the big picture here. Politics is the art of compromise. He can very well be persuaded to vote for a pathway to citizenship ( no matter how much watered-down the final bill might be). As long as there is one, then people can get legalized.
It might take a long time, but if it is done, then in my personal opinion is good.
In short, all i am saying, Senator Gregg could vote for immigration reform.