President Trump has been on a real Twitter tear lately. He's picked fights with "the Squad" — the quartet of progressive first-term Democratic Reps. Alexandria Ocasio-Cortez (N.Y.), Ilhan Omar (Minn.), Rashida Tlaib (Mich.), and Ayanna Pressley (Mass.) — House Oversight Committee Chairman Elijah Cummings (D-Md.), activist and commentator Al Sharpton, and the entire city of Baltimore, with each salvo widely condemned as racist.

It's not just the substance of Trump's latest tweets that have triggered considerable debate. There is also disagreement over the strategy behind them — if indeed any strategy exists at all. Is Trump lashing out blindly? Or is this an appeal to his base?

You don't have to believe Trump is playing three-dimensional chess to see how the president's recent tweets have locked mainstream national Democrats into an embrace of Ocasio-Cortez and the even more controversial Sharpton, which might not sit well with voters. And cable news chyrons blasting Trump as racist will cause his supporters to see liberal media bias and make many millions of them feel like they are also being accused of bigotry.

But it also doesn't require a great deal of imagination to foresee how these tweets could backfire, especially as they proliferate over the course of a long campaign. It might get worse if Trump faces someone other than former Vice President Joe Biden, who would probably be most like Hillary Clinton, on which Trump's strategies were tried, tested, and proven effective. And the two Democrats who at this admittedly early date look best positioned to upset Biden are Sens. Elizabeth Warren (Mass.) and Kamala Harris (Calif.).

Harris is an indefatigable campaigner and can even pass the likeability test when she isn't cross-examining Republicans during Senate committee hearings. Warren is a thoughtful policy entrepreneur who has elicited some conservative praise for hatching plans responsive to the concerns of Trump voters. But both are fashionably liberal on every contentious social issue — sorry, Warren's book Two Income Trap doesn't change this — and highly vulnerable on culture war grounds. With economically liberal but socially conservative voters plentiful in the swing states, that may be why they are also both underperforming Biden in head-to-head matchups against Trump.

Trump should be able to beat either one of them — perhaps even more easily than he bested Clinton — unless he overreaches with attacks that resemble dog whistles less than bullhorns. Trump has already made a caricature of the argument Warren fabricated or at least exaggerated her Native American heritage for her own benefit (and often to the displeasure of Native Americans themselves). Critics dubbed her "Fauxcahontas," which Trump quickly morphed into just "Pocahontas" — and employed at highly inappropriate moments.

Harris was born in California to a father from Jamaica and a mother from India. Online provocateurs have seized on her background to challenge her authenticity as an African-American woman. One needn't channel Nostradamus to predict how this line of attack could appeal to Trump.

Indeed, this is where the dust-up with Cummings over Baltimore is instructive. Trump blasted Cummings' West Baltimore congressional district as a "rodent-infested mess" so badly governed that "no human being would want to live there." Unlike the "America, love it or leave it" sentiments expressed in Trump's previous tweets, this was a form of outreach, however ham-fisted in its execution. Trump was making the argument that black Americans living in our great cities are being ill served by the almost uniformly Democratic elected officials representing them. Yet like Trump's "What the hell do you have to lose?" comments from the 2016 campaign, it sounds at least as insulting to its intended target audience as it does to the elected Democrats and city political machines, especially when it has more to do with Cummings' investigations of the administration than an actual problems Baltimore faces.

Yes, Trump needs white working-class voters to turn out in far greater numbers than they did in the midterm elections. His core supporters appreciate that he is unafraid to be politically incorrect and to take on political rivals even at the risk of being called racist. But Trump also needs a critical mass of suburban Republican-leaners who are pleased with how their 401(k)s are doing to suppress concerns he is racist or sexist and vote their pocketbooks. Trump also needs to hang on to the Latinos who have continued to back him, a vote share hovering around 30 percent nationally, and to do even better in states like Florida and Texas. And Trump would like to make gains with black men, expanding the African-American gender gap former President Barack Obama largely closed.

These voters might be attracted to low minority unemployment, working-class wage growth, and criminal justice reform, while being less bothered by Trump's immigration agenda than the conventional wisdom assumes. They are not the wokest voters in the country. But neither are they likely to swing into the Republican column following an endless stream of racially charged controversies.

Trump's political career up to this point has taught him that fortune favors the bold and pundits are often poor judges of which controversies can derail him. Against some of the Democratic presidential candidates, he may be tempted to overplay his hand.