He's churned up torrents of insults, incited grass-roots Republican fury, fearlessly flouted taboos on gender, race and religion and confounded the pundits again and again.
In a riotous six-month carnival of political incorrectness, Donald Trump has fused his message to the mood of his seething supporters like no other candidate and defied the conventions of a political game under whose rules he should have faded long ago.
Few in Republican Party politics believed when Trump launched his improbable White House bid in June that he'd still be a factor -- much less the factor -- at the end of the year.
"He is a unique political animal who knows his audience and uses controversy as a political weapon better than anyone we have almost ever seen," said Republican political strategist Ford O'Connell.
The brash real-estate developer has emerged as the perfect vessel for the discontent of the mainly white, working-class demographic that sees the nation changing before its eyes -- becoming younger, more racially diverse, more cosmopolitan and in many cases more liberal, as exemplified by the shift on issues like same-sex marriage.
"He knows who his base is. White men who are less likely to have attained a college education -- they see the entire system as corrupt and they don't want any more politics as usual," said O'Connell, the GOP consultant.