The Buchanon retweet is controversial, but I'm sure POTUS would know that.
Buchanon had Pappy Bush on the ropes in the 92 NH primary. After that Perot took off as the anti Bush candidate. Clinton came in second in NH and crowed about being the comeback kid. This was the beginning of the end for Bush. Bush had had insane approval (89%) during the 1st Iraq war. Clinton ended up winning the general with 38% of the vote. Buchanon showing strong in NH changed history.
From stuff I've read, white males left the dem party after Carter. Could be because he seemed like a metrosexual after Nixon (a guy's president) and even the blah Ford (played football for Michigan). Nixon also got the US out of Vietnam, as he had promised, but Carter's draft dodger amnesty (those who left the country) pissed off the 'Nam vets. I've seen some speculation that this movement away from the dems is the reason for the war on men. Again, don't know for sure, but seems plausible to me.
So POTUS looks to going there, pulling of the racist white guy scab. Dems will double down on the racism card and show that they do take the illegals side opposed to white Americans, forgetting that black, Hispanic and Asian Americans are collateral damage. Might be a tie in to POTUS's tweet yesterday that the dem's voter base can't generate enough campaign cash so dems have to fund organizations like PP with taxpayer money and get kickbacks to campaign on,
Looks like POTUS is going to ride the downside and force the dems into a debate which his polling says they are going to lose.