During Michael Vlach's session, "You Might Be a Dispensationalist If," from this month's Shepherd's Conference, he argues that one's convictions on Dispensationalism vs. Covenant Theology necessitate certain conclusions on some matters of doctrine, but not on other matters of doctrine.
He offers Calvinistic soteriology as an example of those non-issues. In doing so, he disagrees with some CT proponents who argue that Dispensationalism necessitates Arminianism. I believe his assessment is correct. One can be a Dispensationalist and a Calvinist.
Vlach doesn't go on to make the observation I'm about to make, and though I've never heard anyone point this out, I can't imagine my thoughts are novel. Here's my point: Dispensationalists don't have to be Arminians, but Arminians (or anyone who denies unconditional election) have to be Dispensationalists.
Why? Well, read Romans 9-11. There is simply no way to hold to a strong discontinuity between how God chose Jacob (not Esau) and Israel (not the other nations of the world) and how God chooses Church Age believers without being a Dispensationalist.
Let me repeat: Dispensationalists don't have to see discontinuity between God's election of Jacob and God's election of believers today. However, if you do see discontinuity on that point—if you think God chose Jacob on the basis of something other than "human will or exertion" (9:16), but you think that God chooses believers today based on some prior knowledge of how they would respond to his universal call, then you simply have to be a Dispensationalist. You have to argue that Romans 9-11 is merely about ethnic Israelites. You have to argue that God doesn't choose people for himself today in the same way he chose them before Christ. You have to be able to unplug the Church from the deep river of OT narratives that clearly and consistently emphasize God's sovereign, unconditional election.
Now, in arguing all those things, I think you do great violence to Paul's argument in Romans. But it's just what you have to do.