Chris Christie Goes Down Swinging at Trump and Pleading With His Party

Chris Christie closed out his second presidential campaign much as he began it, with a blistering and personal takedown of Donald J. Trump designed to prompt a reckoning in his party.

Anticipation had been building all day for the remarks from Mr. Christie, a former governor of New Jersey, after news had spilled out hours earlier that he was telling close allies about his decision.

With all three major cable news networks airing the speech live, Mr. Christie used the rare spotlight — something that had largely eluded his campaign — to make an urgent appeal to the better angels of his party. He framed his animosity toward Mr. Trump in sweeping, historical terms and cast himself as the experienced party elder warning of the possible dangers ahead.

“Imagine just for a moment if 9/11 had happened with Donald Trump behind the desk,” Mr. Christie said. “The first thing he would have done was run to the bunker to protect himself. He would have put himself first before this country, and anyone who is unwilling to say that he is unfit to be president of the United States is unfit themselves to be president of the United States.”