Is this possibly playable with only two players??
I haven't thought much about it but I think it's possible. However, it would require modification of the rules related to elections, the number of starting Senators per player, and distribution of Action Cards. There may be other "balance" issues that aren't coming to mind at the moment.
Also, due to the asymmetric nature of gameplay it wouldn't be nearly as enjoyable. But it might be a way to get used to the mechanics before you find a third interested player.