An anti-amnesty group is working to bring a Grover Norquist-like pledge to the immigration issue, and the highest-profile Republican primary challenger of the cycle is the first to sign.

Mississippi state senator Chris McDaniel endorsed a new pledge from the Federation for American Immigration Reform (FAIR) Monday, vowing to oppose amnesty for illegal aliens as well as increases to legal immigration.

The move could raise the importance of immigration in the bitter race between McDaniel and incumbent Sen. Thad Cochran, who has a mixed record on the issue from the standpoint of anti-amnesty groups.

Cochran’s lifetime voting grade from NumbersUSA, an anti-amnesty group closely associated with FAIR, is C+, lower than all but a handful of Senate Republicans. His rating for the current congress is B+. For his lifetime score, he scored a B for reducing illegal immigration at the borders but an F- for voting against proposals to reduce the number of immigrant visas available via lottery.

FAIR’s new pledge includes three planks. The first is to oppose “any form of work authorization” for illegal aliens. The second is to oppose legislation that would increase the number of legal immigrants. The third is to oppose bills that increase the number of “guest workers.”

Its origin, officials said, was to eliminate the ambiguity surrounding candidates’ immigration views. Republican candidates have sometimes vowed to oppose “amnesty” on the campaign trail, a loaded term that almost no lawmaker says they support, only to vote for bills decried as “amnesty” by immigration hawks once in office.

In an interview, McDaniel, calling amnesty an “absolute no,” said he signed the pledge because increased immigration depresses the wages for American workers.

“What we’ve seen over the past several years is a combination of wage stagnation, growth in welfare programs and even shrinking workforce participation. That comes in large part because of out of control illegal immigration but also because of increased numbers of legal immigration,” McDaniel said. “We have millions of Americans who don’t have a job, plus we have millions who are on public benefits,” he said. “How about we find a way to put those people back to work?”

“It is a form of crony capitalism, and Haley Barbour is dead wrong about this–and by extension Sen. Cochran is dead wrong about this,” McDaniel said. “That’s why you see a number of those individuals [both leftwing and rightwing special interests] who normally don’t share much in common reaching across the aisle and compromising on this issue. But this issue is not subject to compromise. This is one of those issues where we must draw a line in the sand and be strong and courageous,” he added.

Barbour, the former governor of Mississippi and now a lobbyist, is wielding his political machine to help Cochran prevail and is one of the GOP’s top proponents of comprehensive immigration reform.

McDaniel, who voted a handful of times on immigration in the state senate to toughen restrictions, invoked the mantle of some of the senate’s top immigration hawks like Sens. Jeff Sessions (R-AL) and Mike Lee (R-UT). “I’d join Sen. Sessions, I’d join Sen. Lee in every fight,” he said.

Cochran has voted against major pieces of amnesty legislation like the President Ronald Reagan’s bill in 1986, the 2006 bill endorsed by President George W. Bush, and the Senate “Gang of Eight” bill that passed last year.

An old school appropriator who has championed the many earmarks he’s won for his state, Cochran’s chief weakness in a primary is on spending issues. However, he has been criticized by immigration hawks for votes on a series of amendments on the issue and for playing a relatively passive role in the debates.

For example, In 2009, Cochran opposed an amendment from then-Sen. Jim DeMint (R-SC) to a Department of Homeland Security (DHS) appropriations bill that NumbersUSA wrote would have required “that the 700 miles of border fencing (which was previously approved and appropriated for) be completed.”

The DeMint amendment passed 54-44 with over 80 percent of Republicans voting for it, as well as 21 Democrats, or 36 percent of the Democratic caucus. Cochran voted against it.

Last year, while Cochran ultimately voted against final passage and final cloture on the Gang of Eight bill, he did vote to advance the bill on the “motion to proceed.” That procedural measure, which passed without much opposition 82-15, allowed Senate Majority Leader Harry Reid to take the bill to the floor and maneuver it through an organized process to take it to final passage of the bill, 68-32.

“At this point in our history, silence is complicity. If you’re going to be silent in this fight, you’re part of the problem,” McDaniel said.

As close as three days before the June 11, 2013 initial cloture vote, The Hill reported Cochran was “in play” to support the overall package. Cochran’s first statement on the issue posted to his website was June 20, 2013, seven days before the vote on final passage of a bill that had been debated for months.

McDaniel called on Cochran to join him in signing the pledge. “He should courageous enough to engage and sign this pledge–and then fight for those workers,” McDaniel said. A spokesman for Cochran did not respond to a request for comment.