Detroit, Michigan - Rapper Eminem recently joined Barack Obama at a rally for Kamala Harris in his home city, and the two had some harsh words for Donald Trump.

On Tuesday, Slim Shady took the stage at the Huntington Place convention center in downtown Detroit, where he gave a brief address arguing that Trump is against free speech.

"It's important to use your voice," the rapper stated. "I'm encouraging everyone to get out and vote.

"I also think that people shouldn't be afraid to express their opinions," he continued.

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"And I don't think anyone wants an America where people are worried about retribution, of what people will do if you make your opinion known."

While Em didn't mention Trump by name, the former president has been known to use the term "retribution" while speaking about his plans for his presidency.

"I think Vice President Harris supports a future for this country where these freedoms and many others will be protected and upheld," he added before bringing out former President Obama to the stage.

Obama, who is a well-known music lover, told the crowd that following Eminem had him "feeling some kind of way."

"I notice my palms are sweaty, knees weak, arms are heavy, vomit on my sweater already, mom's spaghetti, I'm nervous, but on the surface, I look calm and ready to drop bombs, but I keep on forgetting," Obama said, rhyming the words to the rapper's hit song Lose Yourself.

Obama also took aim at Trump's unfounded claims about mass voter fraud disrupting US elections.

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"Because Donald Trump was willing to spread lies about voter fraud in Michigan, protesters came down, banged on the windows, shouting, 'Let us in. Stop the count,'" he said.

"Poll workers inside being intimidated... all because Donald Trump couldn't accept losing," Obama stated, adding, "There is absolutely no evidence that this man thinks about anybody but himself."

Eminem's endorsement comes as Trump has been facing backlash after he said, "Our whole country will end up being like Detroit if [Harris is] president," which he claimed would be "a mess."