They’ve personally told him or their aides have and he doesn’t think he betrayed any journalistic integrity by naming them...

Rubio, Markowski, Sasse, Collins, Tim Scott, Portman, Blunt, Alexander, Romney, Sasse, Corning, Burr, Thune, Brawn, Grassley.

They were all happy to see him defeated as long as they could keep their majority. He said it on CNN just now

for Kamala

Here is a useful site that I found that explains the process for each state. Ohio is very restrictive

https://www.huffpost.com/entry/mail-in-ballot-vs-in-person-voting_l_5f77aaa6c5b649e564b2c372