In his June 6, 2011 speech declaring his first run for the presidency, former Sen. Rick Santorum didn't mention immigration. On Wednesday, announcing a second race and seeking to win the support of displaced and discouraged American workers, Santorum laid out the toughest position on immigration of any candidate in the large 2016 GOP field.

Speaking at a manufacturing firm in Cabot, Pennsylvania, Santorum described the economic troubles his home state has experienced for decades. "In the late 70s, like many of you, we saw the economic devastation here in southwestern Pennsylvania and across this country, particularly in the area of manufacturing, as a result of the excesses and indifference of big labor, big government, and yes, big business," Santorum said. "We lost 100,000 jobs in what seemed to be overnight. That has to, and did, leave a mark on all of us."

Part of the problem, Santorum said, has been the arrival of millions of unskilled immigrants — legal and illegal — in the United States. "American workers deserve a shot at [good] jobs," Santorum said. "Over the last 20 years, we have brought into this country, legally and illegally, 35 million mostly unskilled workers. And the result, over that same period of time, workers' wages and family incomes have flatlined."

Now business, aided by big-government politicians, is trying to bring even more such workers to the U.S. "Hillary Clinton and big business, they have called for a massive influx in unskilled labor," Santorum continued. "Business does it because they want to control costs. Hillary does it — well, she just wants votes. Their priorities are profits and power. My priority is you, the American worker."

As proof of his bona fides, Santorum pointed to high marks he received recently from the head of the restrictionist group Federation for American Immigration Reform. "Santorum is really the only one who is drilling down into the nuts and bolts and is looking into the job market and how immigration is really hurting American workers," Dan Stein, head of FAIR, said recently during a debate sponsored by the Washington Times.

In his announcement, Santorum touted FAIR's assessment. "Only one candidate got an A [for] standing behind American workers, and he's standing here today," Santorum told the crowd.

Several weeks ago, a Santorum rival, Wisconsin Gov. Scott Walker, stirred controversy when he said the next president and Congress "need to make decisions about a legal immigration system that's based on, first and foremost, on protecting American workers and American wages." Even the suggestion of limiting legal immigration beneath its present level — Walker didn't actually say he would — was enough to cause significant arguments in Republican circles.

Santorum, meanwhile, has been thinking through a position that more clearly calls for new limits on illegal immigration, in addition to the measures against illegal immigration that all Republican candidates support. "I talk not just about illegal immigration, but also what we have to do on the legal side," Santorum told me during an interview in April. "We need limits on some forms of legal immigration that have a negative effect on wages."

With his announcement, Santorum has made immigration a major part of his program to restore American manufacturing and protect blue-collar jobs. He'll need something that works. Far back in the polls, Santorum's campaign will be a test case of whether such an immigration message resonates with enough voters to put him back in the race.