Donald Trump’s endorsement is typically a boon for candidates seeking elected office – a show of support, or disapproval, from the president has proved significant in races across the US this year.

But Trump’s recent comments on the Los Angeles mayor’s race, just weeks before the primary, are sure to benefit Democrats. The president spoke favorably of Spencer Pratt, a former Republican and reality TV star who is polling second in the contest to lead America’s second largest city.

“I’d like to see him do well. I don’t know him. I assume he probably supports me,” Trump told a reporter on Wednesday. “I heard he’s a big Maga person.”

Pratt’s rise has shaken up the mayoral race in the deep-blue city. Best known as the villain of the reality TV hit The Hills, Pratt lost his home in last year’s wildfires and became a vocal critic of the city’s response to the disaster and the leadership of Mayor Karen Bass. Pratt has successfully harnessed anger over the slow pace of recovery, a cost-of-living crisis and an enduring homelessness emergency to advance his campaign.

Pratt is polling second in the race behind Bass, a longtime state lawmaker and congresswoman, community organizer and high-profile Democrat.

Still, Pratt has his work cut out trying to win over skeptical voters and defeat Bass and the progressive city councillor Nithya Raman.

As Zev Yaroslavsky, who spent almost four decades in local politics, recently told the Guardian, the most unpopular person in Los Angeles is Donald Trump. “That’s where Pratt has vulnerability,” Yaroslavsky, who is the director of the Los Angeles initiative at UCLA Luskin’s School of Public Affairs, said in an interview last week.

The city has long been a liberal stronghold. Trump has been particularly unpopular in Los Angeles, even more so after last year, when immigration agents began detaining people in city streets, sparking widespread protests. The president deployed the US military to quell the backlash.

Pratt, previously a registered Republican, has said throughout the campaign he is not Maga, arguing his focus as mayor would be solely on the city rather than national politics.

But his opponents were quick to seize on Trump’s nod of approval.

“Both Trump and Pratt want ICE to invade our city and kidnap our neighbors. I stood up to ICE to protect our communities,” Bass said in response to the news, adding that neither of her challengers are “up to the job”.

Raman said Trump wants a foothold in one of the nation’s most progressive cities.

“It’s no surprise Donald Trump supports his LA Apprentice and ‘Big MAGA person’ Spencer Pratt,” Raman wrote. “Your vote for my campaign stops Spencer Pratt from making it to the general election.”

Pratt cannot come across as a conservative Republican if he wants to win the race, political analysts have said. He has had to tread a fine line as a candidate, acknowledging the support he has received from prominent Republicans while seeking to appeal to a diverse electorate by tapping into the long-brewing frustrations over quality-of-life issues in the city.

In an interview with CNN earlier this week, Pratt said he previously registered as a Republican because the party supported permits for concealed carry weapons. He obtained guns after receiving death threats while he was on reality TV.

The subject of Trump’s support for Pratt came up during an interview on Billy Bush’s podcast.

His priorities are local issues, such as water and power, police, fire department, potholes and sidewalks and streetlights, Pratt said.

“That has nothing to do with national politics or who is in the White House,” he said. “I keep telling people it’s a nonpartisan race.”