If we define the working class this way, there’s no real evidence the Trump era changed the demographic makeup of GOP voters. At least since the 1980s, White working-class Americans have never made up a majority of Republican voters in presidential elections. The share of Republicans who are White and working class has increased slightly in the past few election cycles, but not under Trump. The biggest single-year increase in the White working-class’s share of GOP voters came in 2012, when Mitt Romney was the party’s nominee. Since Romney, the share of White working-class people among GOP voters hasn’t budged. Lower-income White voters without college degrees aren’t a majority of Republican voters, and they aren’t increasing as a share of GOP voters...
Most White working-class voters cast their ballots for Trump in 2016 and 2020. But most also cast ballots for Mitt Romney in 2012, George W. Bush in 2004, George H.W. Bush in 1988 and Ronald Reagan in 1980 and 1984. Other reliable data sources suggest most also voted for John McCain in 2008.
Contrary to the idea that Trump rearranged the political landscape, White working-class support for Republican presidential candidates has been slowly increasing since 1992.
That is, until 2020. Last year’s data suggest that after Trump’s term in office, the rate of White working-class support for the Republican presidential candidate fell for the first time since 2008 — and possibly even earlier, depending on which data source we use. Trump’s presidency actually reversed the long-term trend of growing GOP support within this voting bloc.