I've noticed something this cycle -- or at least I think I have -- that seems to augur a shift in some old presidential conventional wisdom.
The old CW was that Governors and other executive officials had an advantage running for President over Senators and Representatives, because the latter have a voting record one can inevitably comb through to cherry-pick something that sounds bad or controversial.
But this cycle, it seems that its elements of executive experience -- as a district attorney, attorney general, or mayor -- that has created the greatest points of vulnerability for aspiring Democratic candidates. The most damaging hits on Klobuchar and Harris, for instance, have not been Senate votes but rather conduct done as supervising government attorneys. Bloomberg and Buttigieg, of course, only have executive experience, and their programs and policies as mayor have haunted each of them (but especially Bloomberg) throughout the campaign. The fact that supervising executives can be tagged with buck-stops-here responsibility for the acts of subordinates (and often are legally required to sign off -- how ever notionally -- on policies that are in practice taken far below their level), makes it easy to find examples of dodgy or abusive behavior across an entire governmental bureaucracy (a legal argument here, a programmatic decision there) and tie them to the executive official.
I'm not entirely sure what is causing this shift. One possibility is that growing polarization means that politicians have largely given up on getting bills passed via compromise. Whereas in the past Senators and Representatives might have been willing to bite the bullet and vote for imperfect bills that muster bipartisan support by having something for everyone to love and to hate, now there is little incentive to ever vote for something that contains politically unpopular elements just to "get something done".
Another possibility is that actions that are especially within the ambit of executive officials -- most notably criminal justice -- have gone from politically "safe" (nobody ever lost an election by being too tough on crime) to politically precarious (we can now totally imagine folks losing election because they were too tough on crime).
Or maybe there is no so such shift and I'm making it up (or maybe it's a shift that exists in the primaries but will fade come the general). But it seems to me that in this primary, at least, we're seeing far fewer shots fired over this vote, and far more fired over that program. And it's maybe no accident that Senators (or, in Biden's case, former Senators) are dominating the remaining Democratic field (while nary a governor is to be seen). The conventional wisdom that voting records will sink long-standing Senators' presidential ambitions is looking pretty frail.