MANCHESTER, New Hampshire — Pete Buttigieg took heavy fire from his 2020 rivals, who were desperate to blunt his momentum after a stronger-than-expected finish in Iowa.

The six Democrats onstage at the New Hampshire debate Friday night with the former South Bend, Indiana, mayor, touted their own electability and the need for party unity as they tried to counter the 38-year-old’s surge in the state ahead of the primary election next Tuesday.