US election 2024 primaries: intrigue in down-ballot races as Trump-Biden rematch set

Ohio Republicans choose their nominee in key Senate race while California seeks to replace former speaker Kevin McCarthy

With a rematch set between Joe Biden and Donald Trump after both candidates crossed the delegate threshold needed to clinch their parties' presidential nominations, suspense around the next wave of Tuesday primaries shifts to a handful of key down-ballot races.

Five states - Arizona, Florida, Illinois, Kansas and Ohio - will hold their presidential nominating contests on Tuesday. Trump and Biden are expected to sail to victory, growing their delegate counts in a march toward this summer's conventions, where they will officially secure their parties' nomination.