He’s more popular with the swinging soft right voters who move between tory and lib dem (centrist) in the formerly safe tory seats in the south they are now scared they’ll lose. He’s not particularly popular with core tories as he’s a remainer.

The primary reason for the selection is the lack of talent remaining for Sunak to choose from that won’t alienate the voters they need to retain a number of Tory seats. Boris purged anyone who wasn’t a foaming at the mouth brexiter before the last election, leaving Sunak with ideologues like Braverman & Patel to choose from, who are disliked by everyone bar the very hard right (15-20% of voters absolute tops).

At the moment the polls predict a “blue wall” collapse as severe as the “red wall” collapse at the last election. You don’t win back moderates’ votes by lurching ever further right.

Hence, moderate PM is bought back into the fold