An immigration-issues group is mounting a last-minute bid to challenge hundreds of foreign-born voters in Utah's Republican primary Tuesday.

The effort is the work of ProjectUSA, based in Washington, D.C.

The unprecedented challenge, which must be filed with the state elections office today, is part of an effort to unseat 3rd District Rep. Chris Cannon and derail his immigration-reform bills — measures that got a boost Thursday from the Wall Street Journal's editorial board. In its lead editorial, the Journal criticized ProjectUSA and Cannon's GOP opponent, Matt Throckmorton, for their perceived anti-foreigner stance.

The Utah voter challenge would require those singled out in the state's 3rd Congressional District by ProjectUSA to confirm at the polls that they are U.S. citizens and registered voters. The district includes West Valley City and southwestern Salt Lake County, parts of Juab and Utah counties and all of Sanpete, Millard, Sevier and Beaver counties.

State elections director Amy Naccarato is concerned ProjectUSA might scare off some legitimate voters.

"This is definitely, I think, bordering on voter intimidation," she said. "Look at my last name, Naccarato. If someone were to challenge my right to vote, that would probably be upsetting."

ProjectUSA wants tougher immigration laws than those proposed by Cannon. ProjectUSA president Craig Nelsen said a 1999 law that allowed residents to obtain driver's licenses without a Social Security number "opened up Utah's voting system to massive fraud."

Ironically, ProjectUSA's efforts support Cannon's challenger, Throckmorton, who now says he unwittingly voted for the the driver's license law when he was in the state Legislature. Cannon is airing two radio ads about Throckmorton's vote, calling him the one "soft" on international borders.

However, Throckmorton said the vote was unanimous (68-0 in the House, 23-0 in the Senate) because most lawmakers didn't realize a bill meant to help privacy-conscious Utahns protect their Social Security numbers also would allow illegal immigrants to apply for Utah driver's licenses.

ProjectUSA's challenge comes days after a revelation that a Cannon aide, speaking last month on a Utah Spanish-language radio station, urged undocumented workers to donate to Cannon's campaign, a violation of federal election laws.

"If you are undocumented, we welcome this money, but you have to find someone who is legal in order to donate money," Marco Diaz said, according to a partial transcript of the show.