“Senator Joseph McCarthy, meanwhile, helped popularize the term.

Over the decades, the Democratic party became associated w liberal policies, & eventually, “the ‘Democrat party’ slur became a condemnation of liberalism itself”..The phrase was a huge hit in the 90s and 2000s; Newt Gingrich, Rush Limbaugh and George W Bush played it on repeat. By the following decade, Trump was mandating the word: “The Democrat party. Not Democratic. It’s Democrat. We have to do that.”
https://www.theguardian.com/us-news/article/2024/sep/05/democrat-party-republicans

The strangest insult in US politics: why do Republicans call it ‘the Democrat party’?

For almost a century, opponents have removed the ‘ic’ from ‘Democratic’. Is it doing them any good?

^{Matthew Cantor (The Guardian)}