(WASHINGTON) -- The forces that helped to bring down a proposed sweeping overhaul of the U.S. immigration system in 2007 are quietly mobilizing to do the same again.
As President Obama prepares to use his State of the Union address on Tuesday night to appeal for expanded legal U.S. immigration and a path to citizenship for millions of undocumented immigrants already in the U.S., activists are lining up their legions of supporters to fight it.
"In 2007, when callers shut down the Senate phone lines and stopped the amnesty bill in its tracks, we had 350,000 members. We've now got 1.4 million," said Rosemary Jenks, chief lobbyist for NumbersUSA, which led the shut-down effort six years ago.
"Our goal is to make sure that every one of those 1.4 million people, plus anyone else we can find, will be faxing their members of Congress, calling their members of Congress, emailing their members of Congress, and making it absolutely clear that the American people are not onboard with this," she said.
Jenks and other advocates for a more restrained U.S. immigration policy say they're unconvinced that a changed American political landscape following the 2012 election, or a reinvigorated bipartisan coalition on immigration reform, means passage of a landmark immigration bill this year is inevitable.
Instead, they describe familiar flaws in current proposals, which they claim won't stand up to public scrutiny.
"It's hard to get people rallying when there isn't even a legislative vehicle yet," said Ira Mehlman of the 250,000-member Federation for American Immigration Reform. "But what happened in 2006 and 2007 is that the information got out -- this is what's in the bill, this is why it's bad for you, here are all the gaping holes -- and the bill went down."
Obama has made comprehensive immigration reform, including a pathway to citizenship for the nation's 11 million undocumented immigrants, a top second-term priority -- one of the few to have won early bipartisan support.
A coalition of Republican and Democratic senators has unveiled a similar immigration reform plan, with a Senate committee holding the first public hearings on possible legislation on Wednesday.
The national debate on immigration has, so far, lacked a groundswell of grassroots opposition, with much attention focused on the union of unusual political allies, such as Republican Sens. Marco Rubio and John McCain, and Democratic Sens. Dick Durbin and Chuck Schumer.
But opponents say once details of legislation are put down on paper, a spirited movement against the plan would be only a matter of time.
Copyright 2013 ABC News Radio