Or at least that's what most Political Scientists think. Just as I did with the House Races here , below I plot the predictions of a few different political science forecasts, with a couple of media forecasts thrown in for good measure. The big red line is the line the Republicans are shooting for--the number of seats that marks when the Republicans take over the Senate.
As you can see, no current Political Science forecasts (at least that I can find) predict a Republican takeover. The average of all of these forecasts suggests that the Republicans will gain a little over 6 seats--enough to make the Republicans happy, but not enough to take over the chamber. The Abramowitz and Holbrook forecasts rely on fundamental conditions that are outside of the candidates' control--things like the state of the economy, the President's approval rating, etc. The 538 forecast uses a combination of individual race factors, and bigger, "macro-level" factors. The Sabato forecast relies on his estimation of how individual races will go.