You can declare yourself to be any party and vote in that party's primary election.
You switch parties to screw an incumbent you hate.
In Missouri about twenty years ago a lot of Republicans switched to Democrat to vote against governor Bob Holden.
That brilliant move gave us governor Claire McCaskill.
The rest is history.
claire was never governor of missouri....even this missouri hillbilly knows that
It was the 2004 Governor’s race. Republicans did help McCaskill win the primary against Holden, but Matt Blunt beat McCaskill in the general election. McCaskill became a senator in 2006 when she ran against Jim Talent. Both easily won their primaries; McCaskill won the general election. In the 2012 senate race, Democrats voted for Todd Akin in the Republican primary because he was the weakest candidate. Akin won the primary but was beaten by Claire McCaskill in the general election. Fortunately, Josh Hawley beat McCaskill in 2018.
[That brilliant move gave us governor Claire McCaskill.]
I’m sure you meant to type “senator”
But yeah......yuck