Barack H. Obama has tossed aside a custom most presidents have followed since leaving the most powerful office in the world … which is to avoid criticizing their successors in office.

But I’ll offer this caveat. Donald J. Trump has richly earned every single punch line, every joke that has been hurled at him. Why? Because he has spent his entire time in office singling out former Presidents Obama and Joe Biden — his two immediate successors– for unfounded attacks on their character, their intelligence, their staying power and stamina and their policies.

So, in that regard, what goes around has come around with a vengeance.

I will hand it to former President Obama. The man can deliver a scathing attack like no other. He recently campaigned for candidates in Ohio and Michigan in which he wondered out loud about Trump’s fixation with gold. The POTUS, according to Obama, has plastered the White House with so much gold, it’s as if “Saddam Hussein has opened a Cheesecake Factory” at 1600 Pennsylvania Ave. He said Trump should be a regular on HGTV, given his penchant for “home remodeling.”

Under normal circumstances, I might be inclined to urge Obama to give it a rest. These circumstances clearly aren’t normal. Trump seeks to create an oligarchy, scarfing up power and riches for himself and his family, which I believe is unconstitutional.

So it will go, likely for the duration of the midterm election campaign. My reaction to the role President Obama is likely to play down the stretch? Bring it, Mr. President!