When we officially launched our forecast model two weeks ago, it had Republicans with a 64 percent chance of taking over the Senate after this fall’s elections. Now Republican chances are about 55 percent instead. We’ve never quite settled on the semantics of when to call an election a “tossup.” A sports bettor or poker player would grimace and probably take a 55-45 edge. But this Senate race is pretty darned close.What’s happened? The chart below lists the change in our forecast in each state between Sept. 3 (when our model launched) and our current (Sept. 15) update. silver-datalab-dem-senate-prob Read More.Source: Five Thirty Eight/Nate Silver