It's time to fact check the most heated Senate race in the country staff via USA Today 

Colorado's Senate race pits Democratic Sen. Mark Udall against Republican Rep. Cory Gardner, who is in his second term in the House.

The advertising battle has largely focused on women's issues, including birth control and abortion. As a late September Denver Post article noted, if the race were a movie, "the set would be a gynecologist's office."

The focus is at least partly due to an anti-abortion "personhood" initiative that's once again on the ballot in Colorado after having been defeated twice previously. Gardner announced in March that he no longer supported the state measure, because it could, as opponents have said, lead to a ban on some forms of birth control. Ever since, the Udall campaign has released ad after ad on the issue, and Gardner kept the birth-control theme going when he called for the sale of birth control pills over-the-counter without a prescription.

Beyond confusing, and misleading, contraception claims, we've fact-checked third-party ads attacking Udall on the Affordable Care Act and energy. Here are our findings so far in this tossup race.

Claim: Gardner embarked on an "eight-year crusade that would ban birth control."

Facts: Gardner supported anti-abortion measures that don't explicitly call for a ban on birth control but could lead to some forms of birth control being illegal.

The claim, made in numerous ads by the Udall campaign, refers to Gardner's support for past personhood initiatives in Colorado, which defined a person as "any human being from the moment of fertilization," or the "beginning of the biological development." Gardner supported these measures in 2008 and 2010 and said on a2006 questionnaire for Colorado Right to Life that he would support a federal personhood bill.

A personhood measure is again on the ballot in Colorado this November. However, Gardner has withdrawn his support, saying that he now agrees that the personhood measure "can ban common forms of contraception." He remains, though, a co-sponsor of the federal Life at Conception Act, which similarly defines "human person" from the "moment of fertilization."

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