Yuval Levin explains at National Review Online how the activity of a single day offers valuable, but disturbing, insights about the last two American presidents.

It’s easy to criticize, and it’s hard to be president, but surely it’s worth learning from what doesn’t work.

The first lesson came from former president Barack Obama. His intervention in the DACA debate … was a stark reminder of the peculiar combination of recklessness and moral preening that so often characterized his approach to the presidency. He took no responsibility for the situation he did so much to create; he just lectured the people who are stuck with it.

In immigration, as in health care, Obama left behind a legacy teetering on the edge of collapse—a series of policies that could hardly survive except through extreme efforts by a successor both equally committed to their ends and equally willing to pursue super-legal means to sustain them. …

… In the case of DACA in particular, just as with the cost-sharing reduction payments in Obamacare, it frankly seems as though Donald Trump actually wants to keep his predecessor’s policies intact, but in both cases this could not be done without defending the legally indefensible. There are many, many good reasons to criticize Donald Trump, but his reticence to persist in his predecessor’s lawlessness just isn’t one of them.

The sight of so many of those who have been (at times surely rightly) complaining for eight months about threats to our system and to democratic norms now lining up to condemn the Trump administration’s reluctance to ignore the Constitution has to make us wonder about their own commitments. …

… And then, before the day was done, we also got quite a reminder … about one of the key problems with Trumpism. Whatever you think about DACA and whatever you think about the changes to it that the Trump administration announced yesterday, there is no way to understand this tweet by the president last night as anything other than a spectacular blunder that makes a complete hash of everything his administration and his allies might be after.

The president’s statement contradicted both the substance of the policy Attorney General Jeff Sessions announced yesterday and everything Sessions said about it. It makes a mockery of what the president’s press secretary said in defense of it. It defines legislation to “legalize DACA” as the goal, rather than as a concession to be made in return for achieving other policy goals, so that Republicans must now effectively negotiate without leverage and while standing to the right of a famously immigration-hawk president and Democrats can make an “even Donald Trump” argument for not giving an inch. He has given ground decisively but gained no friends and no concessions. And so he has increased the likelihood that six months from now he will be right back here but weaker.