This year, it's just the two of them.
Arnold, 67, is a retired LaPorte County sheriff who has been the district's state senator since 2007.
"I think I'm getting a little more confident each session," he said, "and I think I'm making more of an impact."
Spenner, 81, is a retired high school and college teacher.
"I will vote the way I'm asked to vote by my constituents," she said.
Arnold and Spenner will be on the ballot for the May 8 primary. The winner will face the Republican primary winner -- either Austin Griffin, of LaPorte, or Eric Harris, of South Bend -- in the general election.
Arnold grew up in Michigan City, graduated from Elston High School and served four years in the Air Force before beginning his career in law enforcement.
He holds a bachelor's degree in political science and history from Valparaiso University and a paralegal certificate from Indiana University.
He and his wife, Lauren, live in LaPorte. They have seven children and 11 grandchildren.
"I bring a long history of public service, understanding how the system works, understanding the need for communication," Arnold said, adding that he has been an advocate for better communication between Democrats and Republicans in the General Assembly.
Spenner grew up as the sixth of 14 children on a 20-acre farm near Wheatfield, Ind. She went on to earn bachelor's and master's degrees in education at Ball State University.
She and her husband, Eugene, now deceased, raised two sons in LaPorte. She has two grandchildren.
As a teacher, Spenner said she worked with people of all ages and income levels, and she wants to bring that perspective to the Statehouse.
"I believe I understand the needs of the people," she said. "I think in the legislature, someone needs to go down there and inform them of how the rest of the real world lives."
Spenner said people can't afford to pay more taxes, and lawmakers should focus especially on lowering the sales-tax rate. They also should prioritize adult education as a way to help prepare Hoosiers for work, she said.
Arnold said jobs and the economy are "without a doubt" the biggest issues in this election year.
Staff writer Kevin Allen: email@example.com 574-235-6244