In 2006-2007, the last time Congress seriously considered immigration reform legislation, anti-immigration groups overwhelmed their pro-immigration counterparts and effectively killed efforts to modernize the immigration system. This time, the story is reversed. Pro-immigration groups are dogging Congressmen at town hall events. Anti-immigration rallies have been a complete dud with almost no one showing up while pro-immigration rallies have been attended by thousands. And there is little indication any Republicans who have staked out pro-reform positions have been the subject of a serious backlash. The conventional wisdom has been that Republicans from conservative districts who embraced reform would pay a dear political price. But that's not happening.

It might be because anti-immigrants in the GOP are a minority within their party. From the CBS News:
Meanwhile the latest CBS News poll showed conservative opposition to reform and to a path to citizenship is not really materializing. Much as they did this spring, seven in ten conservatives are willing to accept a "path to citizenship" for undocumented immigrants with conditions. They're not as supportive as liberals, but they're mostly supportive nonetheless.

A critical part of the GOP base, evangelical Christians, also support a path to citizenship (75 percent) taking cues from some of the community's leadership - which may further inoculate House members.
And a poll released last week by a Republican pro-reform group interviewed Republican primary voters specifically, and also found willingness to accept a path to citizenship, and not much fervor for opposition.
"A solid 65 percent majority of Republicans support a pathway to citizenship for illegal immigrants if it is coupled with substantially increased border security," according to the poll by Americans for a Conservative Direction.

Pro-immigration groups have really done well this year in no small part because of effectively using social media. Anti-immigration groups have been able to mobilize in the past by getting their supporters to call, fax and email members of Congress and to show up for town hall events. But they seem to lack the energy even to effectively use those tools and their social media advocacy has been lacking. They just don't intimidate like they used to.

UPDATE: Ted Hesson of ABC News has a good article today on this same subject that can be found here.