SALT LAKE CITY — A Republican computer science professor seeking to fill Rep. Jason Chaffetz's congressional seat is suing the state of Utah after being blocked from filing candidate forms from abroad.

Attorneys for Chia-Chi Teng filed the civil suit in 3rd District Court Tuesday against the state and Utah Lt. Gov. Spencer Cox, whose office oversees elections.

Teng, who is in China running a summer course for Brigham Young University students, is not new to 3rd District voters.

He challenged Chaffetz in last year's Republican primary but lost by a 4-to-1 margin. This year, he was hoping to join a crowded field of candidates vying to represent the district. Chaffetz plans to finish his fifth term June 30.

But a fast-track election process announced during Teng's stint in China barred him from competing.

The deadline to file with the state Elections Office was Friday, a week after the state released details for the plan to choose Utah's new representative in the U.S. House.

Teng, whose teaching stint in China began May 7 and is to end June 18,"was unable to file in person within the short time period announced," according to the suit. The Utah County professor sent his son to file on his behalf and he joined by video conference.

But state elections officers said no.

Utah law requires candidates to show up in person to do the paperwork and take an oath in order to run for office, Mark Thomas, Utah elections director, said Wednesday.

That goes for typical elections and for the Nov. 7 special election.

"It's a statutory requirement that's been in place for a long time," Thomas said.

The law makes exceptions for candidates who are away for military service or for a reason related to their current state or federal job. But no such loophole exists for people who are out of Utah on private business, Thomas said.

Teng's lawyers said in court filings the difference puts an unfair burden on those who are not public employees and doesn't provide justifications for the extra requirements. They said the requirement caused Teng "irreparable harm."

The attorneys asked a judge to reject a state law requiring in-person filing, saying it is so restrictive that is unconstitutional. They also want the court to force Utah to recognize Teng's candidacy, giving him extra time to collect signatures.

Teng, 54, is a former Microsoft software engineer and native of Taiwan. He spent more than $500,000 of his own money in his first bid for elected office last year.

The suit seeks other unspecified relief for the information technology instructor, who is teaching 20 students in the BYU program.

The field to replace Chaffetz has 21 party-affiliated candidates. They include 15 Republicans, three Democrats, two Independent American Party members and one Libertarian. Unaffiliated candidates have until June 12 to declare their candidacy.

The state has until by June 9 to file a response.