What to Watch in Primaries in Georgia, Kentucky, Idaho and Oregon

Voters are headed to the polls on Tuesday in several states.

In California’s 20th Congressional District, the most conservative in the state, two Republicans will face off in a special election to determine who will temporarily fill the seat of Representative Kevin McCarthy, who was ousted as House speaker last year and then resigned. The winner will serve until January, when the next Congress is sworn in. Vince Fong, a state lawmaker and onetime aide to Mr. McCarthy, had a significant lead in the primary. He will face Mike Boudreaux, the longtime sheriff of Tulare County. (They will face each other again in the fall in the quest for a full term.)

Georgia, Kentucky, Oregon and Idaho have primary contests today. In Kentucky and Oregon, voters will also weigh in on the presidential primaries, raising the possibility of protest votes against both President Biden and former President Donald J. Trump.

Here is what else to watch.

The Trump prosecutor Fani Willis will be on the ballot in Georgia.

Fani T. Willis, the Fulton County district attorney, will face a challenger in the Democratic primary for her position. Her opponent is Christian Wise Smith, a lawyer who placed third in the primary against Ms. Willis in 2020 and was defeated in the 2022 Democratic primary for attorney general in Georgia.

Scott McAfee, the judge overseeing Mr. Trump’s trial in Georgia, is also in a competitive race against Robert Patillo II, a civil rights lawyer and radio host. A third candidate, Tiffani Johnson, was disqualified and is fighting that decision.

A progressive vies for a rematch in a swing district in Oregon

Jamie McLeod-Skinner, a progressive challenger, knocked out a moderate seven-term Democratic representative in Oregon’s Fifth Congressional District during the 2022 primaries, but ultimately lost to her Republican opponent, Lori Chavez-DeRemer, by a two-point margin — a result that contributed to Republicans’ taking a thin majority in the House that year.

Now Ms. McLeod-Skinner is facing another Democratic challenger, Janelle Bynum, who has been endorsed by Gov. Tina Kotek. Ms. Chavez-DeRemer is unopposed in the Republican primary.

Three Democrats are also competing to replace Representative Earl Blumenauer, who is retiring after serving for decades in the heavily Democratic Third Congressional District: Susheela Jayapal, a former county commissioner and the sister of Representative Pramila Jayapal, as well as State Representative Maxine Dexter and a Gresham city councilor, Eddy Morales.

And in Multnomah County, which includes Portland, the progressive district attorney Mike Schmidt faces a challenge from a prosecutor in his office, Nathan Vasquez, who is running a tough-on-crime campaign.

Many Democratic and Republican presidential candidates are still on the ballot in Kentucky.

Many presidential candidates who have ended their campaigns are still on the ballot in Kentucky, giving voters plenty of opportunity to cast a protest vote against their parties’ presumed nominees — though Kentucky is by no means a swing state. Mr. Trump will be on the ballot alongside Gov. Ron DeSantis of Florida, former Gov. Nikki Haley of South Carolina, former Gov. Chris Christie of New Jersey, Vivek Ramaswamy and Ryan Binkley. Mr. Biden will be on the ballot with Representative Dean Phillips and Marianne Williamson.