Jose A Delreal Jenna Johnson The Washington Post

Donald Trump on Thursday expressed regret over causing "personal pain" through ill-chosen words he has used "in the heat of debate," an unexpected and uncharacteristic declaration of remorse for a candidate whose public persona is defined by his combative and bombastic style.

A nasty feud that escalated Thursday between Donald Trump and his chief Republican rival over their wives set off a new wave of alarm among establishment Republicans, who fear the GOP front-runner would drive away female voters in a general-election fight with likely Democratic nominee Hillary Clinton.

Donald Trump on Thursday expressed regret over causing "personal pain" through ill-chosen words he has used "in the heat of debate," an unexpected and uncharacteristic declaration of remorse for a candidate whose public persona is defined by his combative and bombastic style.

A nasty feud that escalated Thursday between Donald Trump and his chief Republican rival over their wives set off a new wave of alarm among establishment Republicans, who fear the GOP front-runner would drive away female voters in a general-election fight with likely Democratic nominee Hillary Clinton.