Republicans, hoping to gain seats in the Senate, knew that their limited appeal among minorities would be a problem, as would party infighting. But they did not expect to be derailed by the definition of rape.

Comments by two Republican Senate candidates concerning pregnancies that result from rape — which came after months of battles in Congress over abortion, financing for contraception and a once-innocuous piece of legislation to protect victims of domestic violence — turned contagious as one Senate candidate after another fell short of victory.

In Indiana and Missouri, where voters are reliably conservative, Republicans lost their Senate battles even as many of those voters rejected President Obama. In Wisconsin, the Republican candidate, a former governor, lost to a female lawmaker who is decidedly more liberal than much of the state. In Connecticut, women over all turned against a Republican candidate who frequently reminded voters that she was a grandmother.

Being a woman did not offset being a Republican when it came to winning many Congressional seats among female voters. While one Republican woman, Deb Fischer of Nebraska, will join the Senate in January, Democrats will add four women as senators, including Heidi Heitkamp, who was declared the winner in the race for North Dakota’s open Senate seat, the last undecided contest. There are currently 17 women in the Senate; two of them, both Republicans, are retiring.