The spending was dominated by Trump-aligned and pro-Israel groups, which targeted Massie with negative ads."It really shows us that Trump has a lot of political power over the Republican base even though his popularity with the American public, more broadly, is declining," Smith said.Midterm elections are often a referendum on the president in office But the dynamics shift in general elections, where independents and moderate voters play a larger role.A recent Politico poll found Trump's endorsement could do more harm than good for Republicans in swing districts, by motivating more anti-Trump voters to turn out.Republicans in those areas may seek to run more independent-styled campaigns, Smith said.However, in districts like Massie's — in deep red Kentucky — Republicans are likely less concerned about losing to Democrats."The only real contest there is the primaries," Smith said