There was, yes, a sinister genius at work when Trump used birtherism to build a primary-season constituency in 2016. But since then, his race-baiting has clearly contributed to his chronic unpopularity, and his re-election chances would almost certainly be far better if he talked like George W. Bush on race instead.
Consider two data points. First, even if he’s forced conservatives to excuse statements they once would have denounced, there’s no sign that Trump’s rhetoric has generally boosted white America’s sense of racial grievance. Instead, polls show that even among Republicans, let alone independents, racial stereotypes have softened under Trump. Which means that the political landscape is less favorable to something like his war with Elijah Cummings than it would have been four years ago.
Second, in 2016 Trump won many millions of voters who disapproved of him. But in recent 2020 polling, Trump is performing below his job approval rating in many head-to-head matchups, which suggests that voters who would be responsive to the “policy status quo” argument keep getting turned off by the president’s rhetoric. The supposedly-brilliant strategy of racial polarization, then, is probably just a self-inflicted wound.