Gilstrap will try to regain the seat he held -- as a Democrat -- from 1996 to 2008 before losing it to Democrat Kelly Kultala. Fitzgerald is on his third run for the Kansas Senate seat after being defeated by Gilstrap in 2004 and Kultala in 2008.
The Kansas Senate District represents parts of Leavenworth and parts of Wyandotte County.
Both candidates have said they want no tax increases and will seek to reduce unnecessary regulation that is harmful to business. Both also say they want to stop illegal immigration and support Second Amendment rights. Both are endorsed by Kansans for Life.
And both candidates point to Gilstrap's past experience as a state senator as the difference between them.
Gilstrap says his time in office provided valuable experience, but Fitzgerald says Gilstrap's experience was as a Democrat, not a Republican.
In 2008, Gilstrap endorsed Fitzgerald's campaign after losing the Democratic primary, in which the governor opposed his re-election. He then became a Republican.
Fitzgerald lists improvement of public infrastructure as an important issue for his campaign, as well as the state's role in defending family values.
Gilstrap supports more local control of school funds.
He described his record as that of a conservative Democrat who never voted for a tax increase and voted for the coal plant in Holcomb, Kan,. even though it displeased the governor at the time, Kathleen Sebelius.
The winner of the primary will run against Kultala in the general election.