The G.O.P. primary is a 10-way race to replace the incumbent Republican, Representative Ted Yoho, who is not seeking re-election in this safely red district in northern Florida.

One of the few Florida seats expected to be competitive in November. Alan Cohn, a former local TV news reporter, and State Representative Adam Hattersley are the leading Democrats.

Representative Ross Spano, who is facing a federal investigation of the finances of his 2018 campaign, faces a challenge from Scott Franklin, a Lakeland city commissioner who is endorsed by Representative Matt Gaetz of Florida, a high-profile Trump ally.

Nine G.O.P. candidates are seeking to replace Representative Francis Rooney, who is retiring. Mr. Rooney, a moderate on climate change, has sometimes been critical of President Trump.

This will be a competitive race in November; Mayor Carlos Gimenez of Miami-Dade County is expected to win the G.O.P. nomination to take on Representative Debbie Mucarsel-Powell.

The winner of the G.O.P. primary is all but certain to replace Senator Michael B. Enzi, who is retiring. Cynthia Lummis, the state’s former at-large representative, is seen as the front-runner.

Al Gross is running as an independent candidate — with the endorsement of state and national Democrats — and is widely expected to win. He would then challenge Senator Dan Sullivan.

Alaskan Independence Party candidates and Democratic candidates appear on the same ballot, but run in separate primaries.

Alyse Galvin, an independent, came within seven points of unseating Representative Don Young, a 24-term incumbent, in 2018. She is again the favorite in the Democratic primary.