Vulnerable Democrats who won say party must follow their path

House Democratic front-liners have a message for leadership as the party grapples with what went wrong in this year’s elections: Follow our example. 

While Democrats were generally wiped out on Election Day — losing the White House and Senate, and failing to flip control of the House — vulnerable Democrats in the lower chamber were a rare bright spot for the party.

Those lawmakers proved highly successful in keeping their seats in tough battleground districts, even in some...