Reminds me of a famous JFK portrait. The one in which he looks to the sky full of hope and vision.

https://images.app.goo.gl/5Yvz4YTY7QuLsSSS8

It's also used on, what I think is his most famous biography, but couldn't find a good img of that book.

If I'm right then the painting is a warning against crossing them, saying "you're next". Considering Bill is in the oval office, I don't think it's a huge stretch that it's JFK, but, just a thought.

https://images.app.goo.gl/8MzTeUu3PYwYrs4r7

You can see the book shelf on the right.

https://images.app.goo.gl/8MzTeUu3PYwYrs4r7

***So I just confirmed it is indeed JFK, but it's a bust rather than a book. Image is of Bills oval office, as recreated by Clinton foundation. https://www.encirclephotos.com/image/oval-office-at-william-clinton-presidential-library-in-little-rock-arkansas/