As the confirmation fight over Brett Kavanaugh ended, the opening rounds of the 2020 Democratic presidential primary began.

Only hours after he cast his vote against Kavanaugh’s confirmation, senator Cory Booker appeared on stage to a crowd of roughly 1,000 people at an Iowa Democratic dinner, where he repeatedly brought the crowd to its feet in the course of a freewheeling 45-minute speech.

It was the first visit to Iowa by the New Jersey senator, who has long been considered a potential top-tier Democratic presidential candidate in 2020, only hours after Donald Trump yet again took shots at him in a campaign rally at Kansas.

Addressing a crowd of loyal Democrats, Booker preached an attitude of resilience in the aftermath of Kavanaugh’s ascension to the supreme court to activists deeply disappointed by the result. It was as much a therapy sessions as a stump speech for a crowd of Democrats approaching tight races across Iowa in just over a month.

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Booker repeated the mantra “stay faithful” that he learned while living in a Newark, New Jersey, project from a woman named Virginia Jones. “She doesn’t allow her inability to do everything to undermine her ability to do something,” Booker said of Jones.

The New Jersey senator called on attendees not to get caught up in a state of “sedentary agitation” – something he confessed to sometimes feeling while “sitting at home late at night watching Rachel [Maddow]”. Instead, he harkened back to the fight for civil rights, talking about the despair felt by activists after Bloody Sunday, when police beat marchers in Selma, Alabama, and repeated the words of Martin Luther King: “The moral arc of the universe is long and it bends towards justice.”

Facebook Twitter Pinterest ‘Great way to introduce himself to Iowa Democrats’: Cory Booker receives rave reaction at the party dinner. Photograph: Charlie Neibergall/AP

The speech received rave reactions from the crowd. Jerry Crawford, a key Iowa Democratic powerbroker, told the Guardian that Booker “stamped himself as a top-tier candidate” and described his remarks as “one of the top five party speeches ever given in Iowa”.

Norm Sterzenbach, a veteran Democratic operative, told the Guardian that Booker “owned the room in a way I haven’t seen at a Democratic dinner in a long time. He was engaging and charismatic.” Sterzenbach particularly noted that instead of evoking “anger”, the New Jersey Democrat took a different tone.

“What we need for the future is aspiration,” Sterzenbach said. “We are missing a leader that understands who we are as Americans, what binds us together. That is the speech he chose to give. It is what this room needed to hear. It was a great way to introduce himself to Iowa Democrats.”

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Tim Gannon, the Democratic nominee for secretary of agriculture in the state, echoed this praise, saying that Booker “brought the kind of optimism that folks needed to hear to be ready to spend the next 31 days working for something positive”.

The speech represented the first stop on a three-day trip that Booker would take across Iowa, which holds the first-in-the-nation caucuses. The New Jersey senator would also stump for candidates across the state, as well as attend a family reunion, a preview of which could be seen tonight as 50 relatives cheered on in the cavernous ballroom.

Speaking to reporters afterwards, Booker dodged the obvious question about a potential presidential bid. When asked if he was running, Booker initially joked: “I do need to get in shape, so I will probably go jogging here in Iowa in the morning.” He added that in “all seriousness, we’re here to focus on the election coming up in 31 days”.

Booker, though, has already taken a number of steps to lay the ground for a potential run and has placed staffers on several campaigns throughout the state, a move that potential presidential candidates have often taken to build up a political infrastructure. He was also well prepared to answer a question about farm policy and the ability of an elected official from an urban state like New Jersey to connect to rural voters.