Seven candidates, including a GOP state representative and the son of a former state senator, have filed to run for a newly vacant state Senate seat in northern Minnesota.

The special election for Senate District 11, triggered by Gov. Tim Walz's decision to appoint DFL state Sen. Tony Lourey as Health and Human Services commissioner, is expected to be hotly contested by both parties.

President Donald Trump won the district by double digits in 2016, even as voters sent the DFL incumbent back for another term. Republicans view the seat as a rare opportunity to potentially expand their one-vote majority in the Senate.

"It's a flip-of-a-coin district; it could go either way," said Senate Majority Leader Paul Gazelka, R-Nisswa. "We're definitely interested in that race."

On the Democratic side, Lourey's son, Stu Lourey, and Michelle Lee, a former TV anchor who ran for Congress last year, will face off in the Jan. 22 primary. Stu Lourey, who has worked for U.S. Sen. Tina Smith and former U.S. Sen. Al Franken, would be the third member of his family to hold the seat. His father succeeded his grandmother, Becky Lourey, who was first elected to the district in 1996.

"I'm proud of my family's commitment to this community and public service. Those are the values I grew up with," Lourey said in announcing his bid. "And I know I have to work hard — knock on thousands of doors, have countless conversations — to earn the support of voters here."

Four Republicans, state Rep. Jason Rarick, local GOP activist Justin Krych and residents Matthias Shir and Pine City Mayor Carl O. Pederson, also filed to run by the 5 p.m. deadline.

Republicans on Tuesday endorsed Rarick, a third-term legislator whose House seat covers half the Senate district. It was unclear late Tuesday if other Republican candidates would withdraw after Rarick's nomination. They have until Wednesday to decide.

John "Sparky" Birrenbach will also be on the general election ballot as a candidate for the Legal Marijuana Now Party.

The Feb. 5 special election will fall just weeks into a new legislative year and three months after the heated November midterms.

Rarick said he has been out knocking on doors in the districts in hopes of combating voter burnout and highlighting the importance of the race. Adding another Republican to the chamber, the Pine City Republican argued, would allow the majority to get more done, especially in cases where some members of the caucus are absent or voting no on a bill.

"Fortunately, in half the district I've got my name out there, having run three times," he said. "So the key is going to be just getting out on weekends and when I'm not here at session, spending all my time up in Carlton County, in St. Louis County, moving as many people as I can."

State law prohibits sitting lawmakers from raising money while the Legislature is in session. But as a candidate for a special election, Rarick is exempted from that ban, according to state Campaign Finance Board Executive Director Jeff Sigurdson.

The 11th Senate District stretches along Minnesota's eastern border north of the Twin Cities metro, covering all of Pine and parts of Carlton, Kanabec and St. Louis counties. The winner of the Feb. 5 special election will fill the remaining two years of Lourey's term, which is up again in 2020.

The Star Tribune's Jeff Hargarten and Jessie Van Berkel contributed to this report.

Torey Van Oot • 612-673-7299