Grassely, Shelby, Feinstein, Cochran, and Reid
If I had to guess for a younger one - I'm going to be bold and say Cruz
Would Cruz be able to survive 40+ years in Texas? Not that I'm a proponent of the "Texas will be blue within the decade!!11!!!" theory, but I have to wonder if a far right extremist will play well there in say...2042.
His re-elections will get more challenging (especially if his ideology stays the same), but it will take
significant opposition to dislodge him, even 20 years down the road.