Republicans have controlled the Senate in most every election in my lifetime and have only recently lost control of the Senate. The voters that have consistently voted for republicans have stayed home in formerly safe GOP states or they opted not to vote for a Senator.
This year persons who make it their life career to study political elections say that voters are finding Senate republican candidates more to their liking.
Rats may vote straight but it won’t matter. Those states that were wrestled away from republican control will be go back in the R column because the pickings are better.
Republicans will win the Senate, Obama will win the presidency.
We will see. I still think the senate will go with the potus winner party.