The Washington PostDemocracy Dies in Darkness

The Senate will go Republican, the election models say

There's at least a seven in ten chance that Republicans will net the six seats the party needs to reclaim the Senate majority heading into the 114th Congress, according to the three major election models that aim to forecast the results of Tuesday's vote.

Live updates: Election 2014

The Washington Post's Election Lab model casts the Republican takeover as a near certainty, giving it a 96 percent probability of happening.  Nate Silver's FiveThirtyEight model says Republicans have a 73 percent chance at the majority, while LEO, the New York Times model, pegs it at 68 percent.

The Post and FiveThirtyEight models have been trending more and more toward a Republican victory over the seven weeks we've been writing on them. The LEO model has largely held steady over the past month or so — as this terrific chart from The Upshot shows:

All three models agree on the six Republican pickups that should hand the GOP the majority — either Tuesday or, potentially, on Dec. 6 after a runoff in Louisiana.  Election Lab, LEO and FiveThirtyEight give Republicans a 70 percent or better chance of winning: Arkansas, Colorado, Louisiana, Montana, South Dakota and West Virginia.  The latter three races are not seriously contested; the former three — Arkansas, Colorado and Louisiana — are places where Democrats continue to believe they have a path to victory even while acknowledging they are not currently ahead.

All three models also agree that Democrats are likely to hold onto North Carolina and New Hampshire, although the former looks more competitive today than it did a week ago, and that Sen. Mitch McConnell (R) is a near-certain victor in Kentucky. (No model has McConnell's chances of winning below 93 percent.)

That leaves four genuine tossups, according to the models.  They are (in alphabetical order):

* Alaska (Democratic controlled): Election Lab 79 percent Republican, LEO 67 percent Republican, FiveThirtyEight 71 percent Republican

* Georgia (Republican controlled): Election Lab 67 percent Republican, LEO 58 percent Republican, FiveThirtyEight 68 percent Republican

* Iowa (D): Election Lab 89 percent Republican, LEO 68 percent Republican, FiveThirtyEight 71 percent Republican

* Kansas (R): Election Lab 97 percent Republican, LEO 51 percent Independent, FiveThirtyEight 54 percent Independent

Kansas is the most obvious outlier between the models — but for good reason. Greg Orman, who is running as an independent against Sen. Pat Roberts (R), has said he will caucus with whichever party is in the majority. Because Election Lab predicts that will be Republicans, the odds reflect the strong likelihood of either Orman or Roberts winning.

Georgia, after moving toward Democrat Michelle Nunn over the last few weeks, moved away from her in these past seven days amid polling that suggests businessman David Perdue (R) is ahead but not over 50 percent. If Perdue (or Nunn) fail to break 50 percent on Tuesday night — a possibility because a third party candidate is winning mid-single digits — they will advance to a Jan. 6 runoff.

Iowa remains the race that all three models agree is the least easily predicted. All three give state Sen. Joni Ernst (R) the edge but the probabilities range from 58 percent to 68 percent — meaning that no one feels too confident about the outcome.  Republicans were significantly boosted by a Des Moines Register poll over the weekend that showed Ernst up seven and both sides believe she has the momentum at the moment.

If Republicans lose Kansas, and that looks like a real possibility, they would need a seventh Democratic pickup for the majority. Alaska and Iowa are the best chances to be majority makers under that scenario.

All three forecasts point to Republicans unifying their control of Congress this year.  Now, it's up to the voters.