ATLANTA — The Cain train has come to a stop.

Herman Cain suspended his bid for the Republican presidential nomination on Saturday following a steady drumbeat of sexual misconduct allegations he said were harming his family and drowning out his ability to deliver his message.

With just one month to go until the lead-off Iowa caucuses, Cain’s announcement is tantamount to a concession. Still, he told supporters, he planned to continue his efforts to influence Washington and announced “Plan B” — what he called a grassroots effort to return government to the people.

Cain denounced the accusations of impropriety against him as “false and unproven” but said that they had been hurtful to his family, particularly his wife, Gloria.

“So as of today, with a lot of prayer and soul-searching, I am suspending my presidential campaign. I am suspending my presidential campaign because of the continued distractions and the continued hurt caused on me and my family,” a tired-looking Cain told about a 400 supporters.

It was a remarkable turnabout for a man that just weeks ago vaulted out of nowhere to the top of the GOP field, fueled by a populist, outsider appeal and his catchy 9-9-9 tax overhaul plan.