“I don’t think there’s any mathematical way, looking at the field and the number of candidates, that there wouldn’t be a runoff,” political strategist David Axelrod told the Tribune last week. Underscoring the slim possibility of a final decision Tuesday night, he said: “I mean, meteorologically there’s a way to get hit by lightning, but that doesn’t mean it’s going to happen.”

The horse rac Axelrod, the architect of former President Barack Obama’s political rise, said he thinks Cook County Board President Toni Preckwinkle likely will secure one of the two runoff spots with the backing of two powerful labor groups: the Chicago Teachers Union and Service Employees Union International.

Early voting numbers by Friday had reached 74,000 and by Monday were expected to exceed the 89,000 early votes cast in 2015. Vote-by-mail, once known as absentee voting, is up. Of the 63,000 who applied to vote by mail — nearly triple the requests made in the last two city elections — about 24,000 ballots had been returned.

One clue may come from Chicago’s voter registration numbers. They’re slightly up, which may add up to more voters heading to the polls. Right now, the city has 1.58 million registered voters on the rolls, up from 1.4 million in 2011 and 1.42 million in 2015 — the last two municipal election years. In 2011, 594,000 voters, or 42 percent of those registered, cast a ballot, while that number dipped to 438,700, or 34 percent of registered voters, in 2015, though the mayoral runoff between incumbent Mayor Rahm Emanuel and challenger Jesus “Chuy” Garcia, now a congressman, drew a whopping 600,000 voters.