Updated 12:56 a.m.

The political fate of incumbent Ald. James Cappleman was unclear late Tuesday after the veteran lawmaker clung to a razor-thin lead over political newcomer Marianne Lalonde for control over Uptown’s 46th Ward.

And he wasn’t the only North Side incumbent teetering on the brink of an upset. Ald. Deborah Mell, scion to one of the last legacy seats on the City Council, trailed challenger Rossana Rodriguez Sanchez by 64 votes with all precincts reporting.

With 100 percent of precincts reporting, it was effectively a 50-50 deadlock between Cappleman and Lalonde, with the incumbent holding a 23-vote lead.

Cappleman, a close ally to Mayor Rahm Emanuel, had held the North Side City Council seat since 2011. Lalonde is a 32-year-old chemist who criticized the alderman on affordable housing and development issues and sent out mailers that declared, “Science Against the Machine.”

“I’m glad I’m in the lead,” Cappleman said in an interview with WBEZ. “We still have to count the mail-in votes. We’ll do that, and we’ll find out what happens. As I do in every race, I’ve always learned from both my challengers. That makes me a better alderman.”

In the first round of voting on Feb. 26, Cappleman had five challengers from his left. He won 44 percent of the vote, which was shy of the majority he would have needed to win outright. Lalonde earned a spot in Tuesday’s runoff with 18 percent.

She billed herself as a progressive alternative for the racially diverse Uptown ward, which for decades has been home to high numbers of low-income and homeless people. But it’s also seen an explosion of new high-end developments in the last decade, some aided by taxpayer subsidies.

During the campaign, Lalonde argued the interests of everyday residents are no longer being represented in the ward. That’s a characterization that Cappleman, 66, a soft-spoken former Franciscan friar and social worker fought to counter.

The alderman argued the ward is moving forward and pointed to a redeveloped Wilson Red Line stop, the creation of an Uptown entertainment district, and the planned restoration of the historic Uptown Theatre, which had been vacant since 1981.

Cappleman also touted crime cleanup in the ward, saying gang fights and shootings used to stop traffic.

“If you’ve been here longer than eight years, you’ve seen a remarkable transformation that you never dreamed possible,” said Cappleman at a March candidates forum.

But what some residents see as progress, others say is pushing out the poor and making the ward a less affordable place to live.

Just across the street from Cappleman’s ward office sits Stewart Elementary, a closed public school now converted to luxury loft apartments that, opponents argue, few who attended the school could ever afford. There has been a dramatic loss of single-room occupancy units in the ward, which historically house people on very low incomes.

Cappleman’s election night watch party was scheduled for a bar and restaurant, Lawrence House, that used to house hundreds of low-income residents. Taxpayer subsidies have helped developers fund some of the projects. Cappleman has argued that development and affordable housing are impacted by forces greater than the alderman.

Lalonde argues developers in the ward should be forced to build more affordable units within their developments. Cappleman countered those on-site units are targeted at middle-income earners — which is why he has allowed developers to pay into a fund aimed at helping house the poorest of the poor, though not necessarily within the ward.

His campaign mailers announced “housing is a human right.”

Cappleman touts that he has helped find permanent housing for 96 homeless residents who had been living under Uptown viaducts before being removed by the city.

Although it’s miles from the ward, the proposed $6 billion Lincoln Yards project also became an issue.

That’s because Cappleman attracted citywide scrutiny — and protests — when he took over as interim chair of the powerful City Council zoning committee after Ald. Danny Solis stepped down from the position amidst an ongoing federal corruption scandal.

Once he took the helm, Cappleman called a hearing on the megaproject, which Emanuel is trying to finalize before he leaves office next month. Cappleman later moved to defer voting on Lincoln Yards, a move Lalonde called “a charade.” In the full City Council vote on the zoning change to allow for the project, Cappleman cast one of 14 no votes.

Cappleman consistently touted his experience and questioned Lalonde’s capacity to lead a ward where she’s lived for less than four years.

Unlike some Democratic machine-dominated wards, the 46th has a legacy of leftist politics in its former alderman of 24 years, Helen Shiller, who was seen as a consistent friend of the poor and thorn in the side of developers.

In a show of unity rarely seen in ward politics, all Cappleman’s challengers supported Lalonde in Tuesday’s race. Lalonde also assembled a slew of progressive endorsements, including from former Democratic Cook County Clerk David Orr, Democratic state Rep. Will Guzzardi, the IVI-IPO and One People’s Campaign. Lalonde was backed by mayoral hopeful Lori Lightfoot early in the race.

Lalonde was out-fundraised nearly four to one in the race, with the Real Deal showing donations to Cappleman spiking after he assumed the powerful interim zoning chair position. He took in at least $70,000 from real estate-related donors in two months.

Meanwhile, in the 33rd Ward, Mell’s bid to hold on to her seat meant questions about her political pedigree as daughter of long-time Ald. Dick Mell and sister of former Illinois First Lady Patti Blagojevich.

Deb Mell, a former state representative, was appointed to her father’s seat in 2013 by Emanuel after Dick Mell resigned from office. In 2015, she avoided a runoff by a mere 17 votes but wasn’t declared the victor for a couple of weeks until absentee ballots had been tabulated.

Sanchez was involved in the 2015 campaign of Tim Meegan, a challenger who nearly forced Mell into a runoff. She’s a democratic socialist backed by the Chicago Teachers Union and SEIU.

In a three-way aldermanic race in February, Rodriguez-Sanchez led Mell by only 83 votes, enough for a 42.1 percent to 41.3 percent spread between the two. But with neither reaching the 50 percent threshold because of the third candidate in that race, Tuesday’s runoff was the result.

The 33rd Ward includes parts of Albany Park, Irving Park, Avondale and Ravenswood Manor.