Hasn’t done much? He’s done more than most senators ever do!
Here’s a list of sponsored legislation.
You can find all of his sponsored legislation here. He’s sponsored 141 pieces of legislation since elected.
Apart from legislative actions, his work outside congress, giving out eye surgeries for low income individuals are all setting him up as being extremely electable.
He just hasn’t been as much in the spotlight because he’s doing good for the sake of doing good, not for attention. Because that’s how it should work.