I don’t think Ernst has been proven long enough to provide the legislative firepower he will need. Nor do I like the “identify politics” game that the Democrats play whereby you think you automatically “get women” by having a woman on the ticket (example: Sarah Palin).
I would add Scott Walker and Rand Paul to the short list, although Walker has no legislative experience he’s sure proven he knows how to get things done with the legislature. Rand Paul has a lot of good ideas and this would put him under the control of a “strong boss” and pull in now only his libertarian fans but many of his fathers.
All things considered I’d guess Rubio and Kasich are near the top of the list.
It’s gonna be Walker. He will say he evolved to support jdt. Like all good squishies should. Oh yeah, Trump takes Wisconsin. Hillary chokes her cat to death in hotel room on Concession night.