2020 presidential candidate Julián Castro said on CBS' "Face the Nation" Sunday that President Trump's "racist" attacks on Rep. Elijah Cummings (D-Md.) and other politicians of color are core to his strategy as the "biggest identity politician that we have seen in the last 50 years."

"There's a pattern here. This guy is the biggest identity politician that we have seen in the last 50 years. He engages in what's known as 'racial priming.' Basically, using this language and taking actions to try and get people to move into their camps by racial and ethnic identity. That's how he thinks he won in 2016, and that's how he thinks he's going to win in 2020. I don't think it's a coincidence that just a few weeks ago he kicked off his 2020 campaign, and here we are with the same playbook that he used in 2016."

Why it matters: Liberals' reliance on "identity politics," or the tendency for people of particular racial, ethnic or social backgrounds to "form exclusive political alliances, moving away from traditional broad-based party politics," is frequently attacked by conservatives, especially through the lens of "political correctness." But as Axios has previously reported, those close to Trump say his race-baiting is premeditated and central to his 2020 strategy.

Go deeper: More on Trump's race-baiting calculations