Nearly half of Chicago voters didn’t choose Brandon Johnson or Paul Vallas Tuesday. Winning them over could be key in April.

Just months ago, few Chicagoans would have expected Paul Vallas or Brandon Johnson to best incumbent Lori Lightfoot and survive to the mayoral runoff election.

But before voters decide which of the two upstarts will claim City Hall, each candidate faces a steep challenge courting the roughly 45% of the electorate who preferred someone else in Tuesday’s first round of balloting.

To become Chicago’s top elected official in the April 4 runoff, Vallas and Johnson will need to expand their bases, raise money to spread their messages and reckon with not-so-distant comments on policing and education that might alienate moderates.

“As two candidates with bases on the extreme left and the extreme right, the one who most effectively gets to the middle is going to be successful,” Thomas Bowen, a Democratic strategist who has worked on Lightfoot’s and Rahm Emanuel’s campaigns, said.

Unofficial election results show Vallas and Johnson had obvious bases of support, with clear room for potential growth. Vallas was strongest in the conservative white bungalow belts along the Northwest and Southwest sides and found backers along the lakefront near downtown. But it was Lightfoot who won all the city’s Black wards, while U.S. Rep. Jesus “Chuy” García was successful in low-voting Latino wards and generated some white lakefront support. Johnson’s best showings were in progressive areas around the northern lakefront, though he also won some Black votes.

Bowen said the largely college-educated bloc of white liberals on the North Side will be listening to how candidates communicate on a variety of issues beyond violence, such as transportation and homelessness.

“Liberal voters in any electorate can change their mind rapidly and in inconsistent ways,” Bowen said. “The thing about that electorate is it’s volatile, and it isn’t just as simple as, ‘Well, crime is the top issue, so that’s determinative that Paul Vallas has won already.’”

Rebecca Williams, a political strategist who works with progressive politicians, agreed that Vallas and Johnson were “two of the more polarizing candidates.” Now, the challenge becomes moving to the middle without compromising beliefs that won them their respective bases, she said.

Johnson has done a “tremendous job of bringing together a rainbow coalition,” Williams added. But his positions — including that he hasn’t promised more cops in response to gun violence — might also box him in, she said.

“I don’t think he brings together an ideologically diverse room,” Williams said. “He’s going to have to say some things that are going to upset his base, who have been really hard in the paint for him because of his position around policing. But if he wants to win this election, he’s absolutely going to need to articulate a public safety plan that’s going to resonate with Black, Latino voters.”

For Johnson, expanding support with white voters along the lakefront and courting Black voters will be critical. To that end, Johnson has sought to highlight remarks Vallas has made about critical race theory where he said such curriculum in schools was harming families and taking emphasis off more important subjects.

His strategy will take a page out of Lightfoot’s book against Vallas as he tries to argue that the former schools chief is a Republican, which Vallas has vehemently denied.

Vallas, meanwhile, is taking steps to counteract the negative attacks against him from the first leg of the campaign and diversify his coalition. After the election, Vallas immediately went to work building up his support and on Thursday secured an endorsement from the popular former Illinois Secretary of State Jesse White.

The only white candidate to jump into the election, Vallas has been courting others in the community too, including his friend Willie Wilson, who won roughly 10% of the vote, mostly from Black neighborhoods. Vallas also received an endorsement from Gery Chico, a Latino former CPS board president who also served in Mayor Richard M. Daley’s administration.

Veteran political consultant Delmarie Cobb said she isn’t surprised by White’s endorsement. But while White is popular, she said, it also gives Johnson an opportunity to argue that the endorsement represents “the politics of old … that got us in this mess in the first place.”

“I think Vallas can consolidate the leaders, and Johnson can consolidate the voters,” Cobb said.

The morning after coming out on top in Tuesday’s election, Vallas demurred on his path to expanding his voter base and said: “Look, my coalition is the entire city.” Johnson, meanwhile, simply told reporters Thursday that his strategy is building a “multicultural, multigenerational movement.”

But even before rolling out the White endorsement, Vallas was already indicating that he was making a serious play for the majority Black wards that went for Lightfoot.

“I actually did well in every ward, and I don’t think Brandon won a single Black ward,” Vallas said Wednesday morning. “So I just want to point that out.”

Johnson went right to work on attempting to build Black support by hitting South Side locations such as a Bronzeville senior center where he tried to charm a crowd of seniors by promising the women a dance on Inauguration Day should he win.

One 76-year-old woman watching Johnson, however, was focused more on his message that grew more impassioned as the candidate scoffed at detractors who said he was too “radical,” listing off campaign promises that included fully funded schools, guaranteed housing and reliable transportation.

“As time went on, it got better and better,” Orema Roark of Bronzeville told Johnson afterward. “You got to get direct to the people.”

Johnson is also vying for Lightfoot’s and García’s endorsements, telling reporters Thursday that he’s in conversations with them but not elaborating further. Such support at this point appears more likely to come from García, who competed with Johnson for the progressive vote yet refrained from digging into his rival as much as Lightfoot and others did.

Before the election, García spoke about the importance of unifying progressive forces.

“I think we’ve got to treat this cycle like a primary where good people came out and debated and showed what they believe in. I think we can unify progressives coming out of this race,” García said. “I, for one, feel that I conducted myself the way I said I would: no friendly fire and stuck to the issues, and I feel great about the prospects for rebuilding a progressive coalition.”

Whether García endorses remains an open question, however, after a disappointing campaign in which he placed fourth. And while García’s strongholds could be an important factor, turnout was low in the city’s majority-Latino wards, which could limit their influence. Johnson already has support from progressive Latinos on the Northwest Side including state Sen. Cristina Pacione-Zayas and U.S. Rep. Delia Ramirez.

Activist Nury Ortega has been an advocate for immigrant rights in the Little Village neighborhood for almost a decade. During the most recent election, Ortega held meetings with parents and other neighbors to discuss the platforms of the candidates but very early on realized that few were interested in voting, she said.

A day after the election, Ortega went over to a restaurant where a group of men often gather to drink coffee. She wanted to know how they felt about Vallas and Johnson.

“It’s from one extreme to the other,” Ortega said. “None of them really speak to them (the Latino community), at least the older ones.”

Those men Ortega met with said they are not planning to vote in April.