There’s no question that President Biden and former President Donald J. Trump will be their respective parties’ nominees, with neither facing any credible challengers, but Tuesday’s primaries could be the ones that make it official.

A strong performance today could officially secure Mr. Trump a majority of delegates to the Republican National Convention, and Mr. Biden could do the same on the Democratic side.

Georgia, Hawaii, Mississippi and Washington State are voting on the Republican side. For Democrats, Georgia, Mississippi, Washington and the Northern Mariana Islands are voting, and Democrats abroad will finish their weeklong process.

Republicans in the Northern Mariana Islands will cast ballots on Friday, followed by Republicans in Guam on Saturday.

Most of the states voting this week are solely holding presidential contests, with primaries for Congress, governorships and other down-ballot races scheduled for the spring or the summer. Mississippi is an exception: Senate and House primaries will be on the ballot there on Tuesday, too.