One fore­bod­ing ex­ample of wait­ing un­til a con­ven­tion to pick a run­ning mate was the 1972 Demo­crat­ic Na­tion­al Con­ven­tion, when George McGov­ern picked Sen. Thomas Eagleton of Mis­souri as his run­ning mate after a late night of vot­ing in which many Demo­crats ex­pressed op­pos­i­tion to McGov­ern. Eagleton was dropped from the tick­et later that year after it was re­vealed he had un­der­gone elec­troshock ther­apy for de­pres­sion.

That also raises an­oth­er po­ten­tial prob­lem with wait­ing to make a veep se­lec­tion un­til the last mo­ment: vet­ting. In their book Double Down: Game Change 2012, Mark Halper­in and John Heile­mann fam­ously de­scribed a vet­ting pro­cess so thor­ough on the part of Mitt Rom­ney’s cam­paign that it knocked New Jer­sey Gov. Chris Christie off the veep list. Vet­ting typ­ic­ally in­volves a rig­or­ous pro­cess of look­ing in­to a pro­spect­ive run­ning mate’s polit­ic­al, fin­an­cial, and per­son­al re­cords. “Hon­estly, though, with Don­ald Trump, is he go­ing to do that? Prob­ably not. He’ll prob­ably just go with someone who he’s com­fort­able with,” said Sherid­an.

In a 2012 Wall Street Journ­al op-ed, Re­pub­lic­an law­yer Ar­thur Cul­va­house, who worked on vice pres­id­en­tial vet­ting over a span of three dec­ades, de­scribed a pro­cess that typ­ic­ally takes around eight weeks per can­did­ate. In 2008, Cul­va­house worked with John Mc­Cain’s cam­paign to vet Sarah Pal­in, which ended up hap­pen­ing over the course of just a week, and with dis­astrous res­ults.