In the first year of Donald Trump’s first term as president in 2017, the share of Americans calling themselves Republicans (or independents who leaned toward the Republican Party) dropped just 2 percentage points — from 42% in 2016 to 40% by Q4 of 2017. I predict it will surprise many people to hear that the Democrats didn’t actually change their advantage in party ID much at all in Trump’s first term, expanding their advantage to +7 in 2018 from +6 in 2016.

In Trump’s second term, however, the Republican Party is shedding members at a much higher pace. Gallup released its latest party identification data this week, and the numbers show Republican identification dropped from 46% in 2024 to just 40% in Q4 of 2025 — a 6-point decline, triple the 2-point drop during Trump’s first term.