2024 race hits critical stretch as debate approaches and first ballots are set to go out

(CNN) — The 2024 presidential race is entering a critical stretch, with Vice President Kamala Harris and former President Donald Trump set to debate and the first swing state ballots hitting mailboxes shortly after the Labor Day holiday weekend.

As the calendar turns to September, both campaigns are focusing on key battleground states — with Harris eyeing an expanded map and Trump digging in across the Upper Midwestern states that delivered him the presidency in 2016 and ousted him from office in 2020.