In the 2020 US elections, Sen. Harris is a major-party VP nominee and could decide to resign from the Senate before November to focus on her campaign. Gov. Newsom gets to appoint her replacement and could presumably pick someone who's on the November ballot, for example Rep. Cox. Under California's top-two rules, would the appointee's opponent, Rep. Valadao in this example, win unopposed?
(I'm not saying this is a likely or wise series of political decisions - I just want to know the rules about this thing. Write-in campaigns aren't allowed in top-two elections - that's all I know.)