The Republican Party has historically leveraged the subject of abortion far more effectively than Democrats. This year, it could cost them control of the Senate.

The Senate has been up for grabs since the beginning of the cycle. Democrats currently control 53 seats, including the two independents in their caucus, but are defending 23 seats to just 10 on the Republican side. The possibilities are multiplied by uncertainty over who will wield the tie-breaking vote—Vice President Joe Biden or Rep. Paul Ryan—and which party Maine independent Angus King will shack up with in the likely event that he wins.

Two major blows have befallen the Republicans since August. First, Todd Akin's campaign imploded over his statement that women rarely get pregnant from "legitimate rape." Now, Senate candidate Richard Mourdock in Indiana is watching his luck nosedive after stating that "even when life begins in that horrible situation of rape, that it is something that God intended to happen." Under the Signal's prediction model, his odds of victory have plummeted 50 points in 36 hours.

Sources: Betfair, Intrade, HuffPost Pollster, RealClearPolitics

Establishment Republicans did not want either candidate on the ticket in the first place. We considered Indiana a safe Republican hold prior to incumbent Richard Lugar's loss to Mourdock in the primary. Akin knocked off a six-term congressman backed by Sarah Palin in the Missouri primary, to the delight of the Democratic incumbent, Sen. Claire McCaskill.