If you want to go fast, Cory Booker was fond of saying, go alone. If you want to go far, he would continue, go together. When it came to his 2020 presidential aspirations, he did neither. Once considered a top prospect for the Democratic nomination, the senator from New Jersey ended his campaign on Monday. He didn’t even make it to Iowa.

"It is with a full heart that I share this news — I’ve made the decision to suspend my campaign for president,” Booker wrote his supporters just weeks before voters officially kick off the election season.

"Nearly one year ago, I got in the race for president because I believed to my core that the answer to the common pain Americans are feeling right now, the answer to Donald Trump’s hatred and division, is to reignite our spirit of common purpose to take on our biggest challenges and build a more just and fair country for everyone," he continued.

Booker still believes in that message, he said, but his team no longer has the “money to scale up and continue building a campaign that can win.” Now out of the race, the former Newark mayor will return full time to the Senate where he manned the ramparts for the Resistance against President Trump and sparked national interest in a potential challenge to him.

It was in the Senate Judiciary Committee that Booker compared himself to a Thracian gladiator who led a revolt against the Roman Empire. During the third day of confirmation hearings for Supreme Court nominee Brett Kavanaugh, the senator said he was breaking the rules by releasing confidential emails from the nominee’s time in the George W. Bush administration. However, the documents were already public. With a national audience watching in real-time, Booker still made a show of challenging his Republican counterparts in the committee.

“This is about the closest I'll probably ever have in my life to an ‘I am Spartacus’ moment," Booker said as Democrats on the panel voiced their support. But the documents proved not to be consequential and Kavanaugh was eventually confirmed. In the end, critics such as Republican Sen. Marco Rubio and  sitting Supreme Court Justice Clarence Thomas mocked the New Jersey lawmaker for trying to “look cute.”

The historical Spartacus, depicted by actor Kirk Douglas in the 1960 film by that name, was crucified.

On the campaign trail, the candidate offered a softer side. “Hope is the act of conviction that despair can never have the last word,” he told a packed ballroom the day that Kavanaugh was confirmed. A chartered jet had ferried Booker from Washington to Iowa for the state Democratic Party’s fall gala, and he assured the crowd that “we are not defined in this state by Republicans in power; we’re defined by how we respond to them.”

Crowds would become increasingly difficult for the candidate to draw after he declared his White House intentions. Booker never broke into the top tier, and on the day of his exit the RealClearPolitics average shows his polling in the basement. Nationally, Booker stood at 1.8% support. In Iowa, just 3%.

His campaign may be a story of a conventional candidate incapable of breaking out in an unconventional field. The senator had an inspiring biography coupled with the kind of soaring rhetoric that inspired voters and, on occasion, brought some to tears. He also had real legislative accomplishments, including the bipartisan criminal justice reform he helped shepherd through the Senate and onto President Trump’s desk.

But Booker was eclipsed by the likes of Andrew Yang, an entrepreneur from Silicon Valley without any governing experience. He was also surpassed by Pete Buttigieg, the now-former mayor of South Bend, Ind., who has never won a statewide race. Both remain in the 2020 contest, and Buttigieg will appear on stage at the last Democratic debate before the Iowa caucuses. Booker did not qualify.

With his exit, the field is less diverse; former Massachusetts Gov. Deval Patrick remains as the only black candidate. Six contenders hit polling and donor thresholds required to appear at Tuesday’s debate and compete for the favor of a party that cherishes diversity. All of them are white.

While several of Booker’s colleagues will continue to split their time between Iowa and Capitol Hill, he can focus his energy entirely on the impeachment trial of the president. He is expected to return to form in tormenting Trump. He will also have to prepare for his own reelection.

Though Booker recently surpassed his fourth-quarter fundraising goal, the funds were not sufficient to continue his presidential bid. His deputy campaign manager, Jenna Lowenstein, encouraged supporters to donate to his Senate campaign.

“Cory Booker's right back in it, running for the U.S. Senate,” she wrote on Twitter shortly after her boss called it quits. “We f***ing need him there.”