One of Flake's strongest lines of attack against Carmona thus far is that he'll be a cookie-cutter Democrat, backing Obama every step of the way, and the first ad push he launched in the general election cycle aimed to label Carmona as "Rubberstamp Rich."

But the Goldwaters' endorsement, which came just hours after the launch of Flake's attack, serves to counter that. And now the Democratic Senatorial Campaign Committee (DSCC) is hoping to stretch the endorsement out to cover not just Carmona's centrist credentials, but also Flake's position on women's issues.

Citing his "no" vote on equal-pay legislation and his vote to allow employers to deny contraception coverage, among others, DSCC spokesman Matt Canter said in a memo that Flake's policies are "dangerous for women."

"These kinds of extreme and draconian policies are far out of the mainstream and would prove to be devastating for women’s healthcare and economic security," Canter said.

Women's issues are one of three key topics the DSCC believes will bring Flake down, according to a strategy memo issued after Tuesday's Arizona primary election.

And the Goldwaters spoke of the importance of women's issues in the race when they endorsed Carmona. Joanne Goldwater called women's rights "the most important issue in this campaign," according to The Associated Press.

But Flake has led in most polls, and the state leans Republican. Democrats hope, however, that the strength of their candidate, who was personally recruited to run by President Obama, and the beating Flake took in the primary could shift the tide in their direction.