If I had to guess, I'd say it looks like Andrew Jackson, who was also maligned as a populist by many pundits of his time when he became President, and whose image Obama was so eager to replace with Harriet Tubman on the $20 bill. I've got nothing against Ms. Tubman, but put her on the $50 bill instead, in place of Grant, who was no great President.

(click on it to enlarge)

As an aside, this brought to mind that when I was a kid, my mother could recite from memory this poem:

"Antigonish" (1899)
by William Hughes Mearns

Yesterday, upon the stair,
I met a man who wasn't there.
He wasn't there again today,
I wish, I wish he'd go away...

When I came home last night at three,
The man was waiting there for me
But when I looked around the hall,
I couldn't see him there at all!
Go away, go away, don't you come back any more!
Go away, go away, and please don't slam the door...

Last night I saw upon the stair,
A little man who wasn't there,
He wasn't there again today
Oh, how I wish he'd go away...