The strong Republicans are all going to go after McCaskill and Galloway has been surprisingly uncontroversial for being an appointee from Jay Nixon.
Galloway is not a major target of the GOP and will likely face a better climate than Missouri Democrats did in 2016. The GOP wants that office obviously.
Only thing that will defeat her is partisanship and staying anonymous. But Galloway's press is positive and fairly frequent.
The county map of her potential victory would be quite interesting. Would be interesting to see if some old yellow dog counties come back to her or if she just racks up margins in suburbs.
She could take Saline near Boone, or Ste. Genevieve, beyond that I don't see what other "yellow-dog" counties she could win.
