Note that he's using the Tucker Carlson version of the Great Replacement Theory. They want to make it a partisan issue, because they don't want White people to wake up to what's going on. The Great Replacement Theory is about replacing White people, not replacing Republicans. Republicans have long supported mass migration of non-Whites into the US. Perhaps the most damaging piece of legislation was the Hart-Cellar Act, which opened the floodgates to non-White immigration. Both parties supported it, but a greater percentage of Republicans in the House and Senate voted for it than Democrats did. It was Republicans who freed the black slaves and made them citizens, rather than deporting them back to Africa. Republicans only started speaking out against racial identity when White began reasserting our racial identity. In the words of Ben Shapiro, "I don't give a good damn about the so-called browning of America."