In late March, the Democratic pollster to whom Rahm Emanuel once sent a dead fish delivered the political version of a dead fish to the mayor: a poll that, Alan Secrest claimed, showed Emanuel was unelectable.

That poll, conducted for mayoral challenger Garry McCarthy, pegged Emanuel’s job performance rating at just 32 percent and the mayor’s favorability rating at 36 percent. Emanuel’s campaign tried to discredit the McCarthy poll by smearing Secrest.

Now, a poll conducted for another mayoral challenger — Lori Lightfoot — shows similar numbers, making the results more difficult for the embattled two-term mayor to ignore.

The telephone survey of 800 Chicago voters deemed “likely” to cast ballots in the February 2019 mayoral election was conducted April 23 to April 26 by pollster Jason McGrath.

It showed that just 31 percent said they would vote to re-elect Emanuel. When respondents were asked to choose between Emanuel and someone new — without mentioning a specific alternative — 62 percent of those surveyed said they wanted to try someone else.

When Emanuel was pitted against “a number of announced and likely candidates in the race,” his numbers went up only to 34 percent — statistically insignificant, given the poll’s margin of error of 3.5 percentage points.

McGrath also did polling for Cook County States Attorney Kim Foxx and for three Democratic members of Congress: Robin Kelly, Cheri Bustos and Raja Krishnamoorthi.

This latest poll was conducted roughly two weeks before Lightfoot declared her candidacy by condemning Emanuel’s autocratic, “us-vs.-them” style of government.

At the time, McCarthy’s 70 percent name recognition vaulted him into second-place, with 16 percent of the vote, followed by Circuit Court Clerk Dorothy Brown with 15 percent and former Chicago Public Schools CEO Paul Vallas with 9 percent.

Lightfoot was in the 2-to-3 percent range, just slightly above County Commissioner Bridget Gainer, who is poised to enter the race in days.

But, when Lightfoot’s background was described, simulating a “modest amount of paid communications,” she moved into second-place.

And when voters were told enough about Lightfoot to simulate a “well-funded campaign” — her status as Emanuel’s preeminent challenger was “solidified” and the former Police Board president managed to consolidate much of the anti-Emanuel sentiment in a head-to-head race, building a 50-to-40 percent lead in a potential run-off.

Secrest has declared Emanuel “unelectable” and said the only way for the mayor to avoid embarrassment would be to retire.

McGrath isn’t going quite that far. But his poll clearly shows how much trouble the mayor is in.

Emanuel survived the 2015 run-off by spending a record $24 million and winning 64 percent of the white vote, 57.3 percent of the black vote and 39 percent among Hispanics.

The Lightfoot poll shows the mayor with just 39 percent support among whites, 31 percent from African-Americans and 26 percent among Hispanics.

His political base, if he still has one, comes from his 47 percent support among voters over 65, with “some residual support” among lakefront whites of all ages. But neither of those voting blocs show Emanuel over the 50 percent mark.

That means another run-off is a virtual certainty. In order to survive a runoff, without getting “stuck somewhere in the low 40’s,” Emanuel must find a way to “repair his reputation with some segment of the electorate that is particularly negative on him right now.”

That’s how much damage has been done by violent crime, schools closings, a sexual abuse scandal at Chicago Public Schools, the mayor’s decision to withhold the Laquan McDonald shooting video until after the 2015 election and by the avalanche of tax increases needed just to begin to solve Chicago’s $36 billion pension crisis.

Emanuel campaign spokesperson Caron Brookens summarily dismissed the Lightfoot poll.

“In politics, the only people who release months-old, stale polling are those who don’t have a good story to tell today,” Brookens wrote in an email.

“Our CURRENT polling shows the Mayor beating all challengers by double digits.”

Lightfoot said the “No. 1 take-away” from her poll is that Chicagoans are “looking for somebody else.”

“I can’t think of any incumbent after two terms and seeking a third term who is mired at 31 percent where 60-some percent of the people surveyed say they want change. Those are really hard numbers to overcome. You’ve got to, frankly, have a different kind of personality and offer people hope for a different, better future,” she said.

“What I keep hearing from people is that Rahm’s expiration date has run. It’s time for change. That’s the most encouraging thing I take from the polling and from what I hear every single day.”

Lightfoot was asked why she is so encouraged, when she is barely known while McCarthy stands solidly in second place.

“There’s nobody else in the race right now or thinking about it who can put together the kind of winning coalition that any candidate needs to be successful,” she said.

“No one wins by just appealing to a narrow demographic. It’s not gonna get you into a runoff. And it’s not gonna get you to victory in a runoff. I’m the only candidate that has the capacity to put together that kind of a coalition because of who I am and the issues I have stood for.”

After raising $503,000 in the second quarter from 700 different contributors, Lightfoot feels “very comfortable” about having enough money to get her message out.

“It’s $500,000-a-week to get on network TV with a full amount of points on a weekly basis. That’s a helluva lot of money. We predict that TV starts sometime in January and runs through Feb. 26. You do the math of what the budget looks like,” she said.

“We’re smart and mindful of that. But, we’re also gonna be really, really creative in the way that we reach out to people.”