MIAMI — As the mayor of reliably Democratic Miami-Dade County in Florida, Carlos A. Gimenez, a Republican, was a pragmatist who avoided partisan politics and in 2016 voted for Hillary Clinton. But after President Trump’s election, things started to change.
Six days after the inauguration in 2017, Mr. Gimenez became the first big-city leader in the country to reverse the county’s de facto status as a “sanctuary” for undocumented immigrants. Critics said he had kowtowed to Mr. Trump and turned his back on the county with the second-highest number of immigrants in the nation, after Los Angeles.
This year, Mr. Gimenez received Mr. Trump’s endorsement, spoke at one of his rallies and was elected to Congress.
His remarkable political evolution mirrored a broader shift in Miami-Dade, where 58 percent of the electorate is Hispanic and Mr. Trump made huge inroads from 2016 to 2020. Hundreds of thousands more people voted for him this year, and though he still lost the county to Joseph R. Biden Jr., he improved his margin over 2016 by 22 percentage points, a swing that helped him easily win Florida and sweep a slew of local Republicans into office.