The chant — “2 cents, 2 cents, 2 cents” — started in the back of a crowd that packed sidewalks at the Iowa State Fair. Elizabeth Warren, basking in the spontaneous adulation of her proposed wealth tax, prompted roars with her call for the ultra-wealthy to “pitch in 2 cents so everybody gets a chance to make it.”

A night before, the Massachusetts senator enjoyed similar treatment when Democrats at a party dinner jumped to their feet — some beginning to dance — at the opening bars of Dolly Parton’s “9 to 5,” the song that would usher Warren on stage.

For someone whose White House ambitions were dismissed by some Democrats earlier this year, Warren’s reception in Iowa this weekend was a clear warning sign to other 2020 candidates that hers is a campaign to be reckoned with in the state that kicks off the race for the party’s nomination.