AURORA, Colo.—Mark Udall's campaign strategy of constantly courting women voters has seen better days. Republicans are ripping the appeal and attempting to turn it against the Senate incumbent. The Denver Post slammed Udall for "an obnoxious one-issue campaign" while endorsing his challenger. And once-promising poll numbers have grown frightening in the race's final weeks.

But Hillary Clinton isn't having any of it.

Campaigning next to Udall in the Denver suburbs Tuesday, the former secretary of State not only reiterated Udall's women-centric strategy, she explicitly took on those who've criticized him for it.

"I've heard, some may wonder why Mark Udall has stressed women's rights in his campaign," Clinton told a crowd of about 1,000 in a hotel ballroom. "I want you to understand that as far as I'm concerned and as far as Mark is concerned, when he's fighting for women's rights, he is fighting on the frontier of freedom. Because women's rights, here at home and around the world, are clearly at risk unless people of goodwill, both women and men, regardless of political ideology, understand that women's rights are like the canaries in the mine."

So as a woman and an American, I think it's a big deal in this election," Clinton continued. "This election is important to everybody, but it's especially important to the women of Colorado."

Udall and his team have repeatedly raised issues of abortion and contraception access in an attempt to paint his Republican challenger, Rep. Cory Gardner, as too conservative for Colorado's evenly divided electorate. Gardner once supported state "personhood" laws defining life as beginning at conception but has said during the campaign that he no longer backs such measures, although his name remains on a federal bill with similar goals.

It's unclear, however, if Udall's attacks are paying off. The Democrat began the campaign as a favorite—if a slight one—but recent polls now place him behind Gardner. The most recent public poll of the race, which showed Gardner leading by 1 percentage point, demonstrated how important women's votes are to Udall: He led by 5 points among women in the poll, but Gardner led by 7 among men.

Republicans have been eager to depict Udall as a one-trick pony. In a recent Senate Republican TV ad in Colorado, a female narrator accuses Udall of running a "single-issue campaign" while ignoring issues such as national security and the threat posed by terrorists in the Middle East.

Clinton, however, stayed on message: "These Democrats will never support so-called personhood laws," Clinton told the rally. ""¦ They won't tell the voters of Colorado one thing about personhood and tell their colleagues in the Republican House of Representatives the opposite about personhood."

Clinton also spoke about the wage gap between men and women. She did, however, also touch on other issues, including praise for Udall's work to combat federal intelligence-gathering efforts. Udall has been among the most vocal Democrats for National Security Agency reform on Capitol Hill but hasn't stressed the issue as hard on the campaign trail.

As with any Clinton appearance, the question of a 2016 presidential run dominated the subtext.

Democratic House candidate Andrew Romanoff welcomed Clinton to the rally by telling the crowd, "Are you ready to hear from the next president of the United States?" And she devoted part of her speech to describing the birth of her granddaughter as a strong personal motivation for staying involved in politics—perhaps, though Clinton never said it herself, as a candidate for president in 2016.

"You think about the kind of future you want for your child and your grandchild, and you think about what kind of state, country, and world you want that child growing up in," Clinton said. "Because you understand quickly that you can do as much as possible for your own child or grandchild, but what's going to be around him or her? What kind of opportunities are going to be around for the people that he or she grows up with? And we know we still have problems that need addressing here in America."

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