Mitt Romney is being criticized for neglecting to mention Sally Ride's partner of 27 years in offering his condolences.

The presumed Republican presidential candidate tweeted on Monday: “Sally Ride ranks among the greatest of pioneers. I count myself among the millions of Americans she inspired with her travels to space.”

Ride, the first American woman in space, passed away at the age of 61 after losing a prolonged 17-month battle with pancreatic cancer. She and Tam O'Shaughnessy became romantically involved in 1985, just two years after she made history as the first American female in space aboard the NASA space shuttle Challenger.

(Related: Sally Ride's partner Tam O'Shaughnessy part of the family, Bear Ride says.)

“Mitt Romney paid tribute to Sally Ride, but neglected to mention her female partner of 27 years or the federal benefits she will be denied,” Logan Decker tweeted in response.

“@MittRomney kind of despicable & grotesque that her partner of 27 years will be denied federal benefits, don't you think?” indie-rock group The Mountain Goats messaged.

Another user commented: “Mitt Romney called Sally Ride a hero. Yet in HIS America, Sally could travel to space but NOT to the court house to marry her life partner.”

“Oh Mitt Romney, Sally Ride is your hero? Too bad her partner gets no benefits or marital rights because she is a woman. Mitt, you are a dick,” tweeted user sarahharbin.