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The campaign of Bruce Braley, the Democratic nominee for Senate in Iowa, released a new ad Wednesday comparing Republican nominee Joni Ernst to a baby chick. Republicans responded to the commercial by pouncing on it as a not-so-subtle indication of sexism.

Braley's spot came in response to an infamous Ernst ad aired during the Republican primary campaign, during which she joked she would be able to "cut pork" in Washington because she "grew up castrating pigs" on Iowa farms. 

"We've all heard the one about pigs squealing, but when Joni Ernst had the chance to something in Iowa, we didn't hear a peep," a narrator says in Braley's ad, cutting to a photo of a baby chick.

Brad Dayspring, a spokesman for the National Republican Senatorial Committee, said the lack of outrage over Braley's ad shows there's a clear double standard.

"Does anyone doubt that if a male Republican candidate ran an ad comparing a female Democratic candidate to a chick, inboxes across Washington would be filled with outraged press releases demanding that the ad be condemned and taken down?" Dayspring said in an email. "Of course not, but for now the outrage kings at the DSCC and their mouthpieces at liberal news organizations remain silent."

Timothy Hagle, a University of Iowa political science professor, agreed with Dayspring's sentiment. He tweeted Wednesday, "Imagine if a GOP candidate had used a 'chick' in an ad against a female opponent."

Braley and Ernst won each of their respective nominations on Tuesday, and will face off in one of the marquee Senate matchups this fall as Republicans eye taking back control of the Senate.

You can watch the full Braley ad below: