Cardi B spoke in favour of Kamala Harris on Friday night as the vice president hosted a rally just seven miles from where Donald Trump addressed supporters in Milwaukee, Wisconsin.
The Republican and Democrat presidential candidates were both out in the swing state ahead of the election on November 5, with polls said to be very close.
Rapper Cardi B said she had not been planning to vote until Ms Harris replaced current POTUS Joe Biden on the ticket - and she is now fully committed to her cause.
"Did you hear what Donny Trump said the other day?" Cardi B said onstage, referring to Trump saying he'll protect women "whether they like it or not."
"Donny, don't," she said. "Please."
She is the latest big name to go into bat for Ms Harris, following Michelle Obama speaking in Michigan and Beyonce coming out in Houston.
Milwaukee is home to the most Democratic votes in Wisconsin, but its conservative suburbs are where most Republicans live and are a critical area for Mr Trump.
"Both candidates recognise that the road to the White House runs directly through Milwaukee County," said Hilario Deleon, chair of the county's Republican Party.
Air Force Two, the vice presidential aircraft, touched down at Milwaukee's airport about 40 minutes ahead of Mr Trump's private plane, which he has dubbed Trump Force One.
The planes parked near each other, but the candidates did not cross paths; Harris' motorcade was gone before Trump landed.
Both venues drew roughly the same number of people, based on crowd estimates provided by each campaign. Mr Trump took the stage seven minutes before Ms Harris.
The two rallies may be the candidates' last appearances in Wisconsin before Election Day.
Both sides say the race is once again tight for the state's 10 electoral votes. Four of the past six presidential elections in Wisconsin have been decided by less than a point, or fewer than 23,000 votes.
Mr Trump railed against the economy under Mr Biden. The US jobs report released Friday, showing that employers added just 12,000 jobs in October, suggests that the Biden-Harris administration is failing the economy, he said.
"This is like a depression," Mr Trump said of the numbers as he heaped insults on Harris.
Economists estimate that Hurricanes Helene and Milton, combined with strikes at Boeing and elsewhere, pushed down net job growth by tens of thousands of jobs in October.
