Good question. The Senate is such a viper's den. I suppose in pecking order (to mix metaphores) would be Florida's Rick Scott. Scott's support of continuing genocide in Ukraine - at our own security risk - has caused me to sour some on our ex-governor. I wrote him and asked him to repent... no showing so far. \_😯_/
Also Scott was in charge of the Republican Senate Campaign Committee, which puts him in close proximity to McConnell's choices for giving... trust erodes away.
John Thune has a title that I recently read that I thought could imply his status as “heir apparent”.
However, titles are probably meaningless for any real advantage, in this current Senate atmosphere.
Also, I believe there are
currently three Democrat Senators knocked out of function. Feinstein, Fetterman & one other are unable to be present or participate in any form.