A relatively unknown independent candidate for U.S. Senate has unexpectedly put the campaign up for grabs in Kansas and complicated the GOP’s attempt to seize control of the Senate in November’s midterm election.

Republicans are labeling Independent candidate Greg Orman a “stealth Democrat,” and anti-choice organizations are attacking his position on reproductive rights and other issues as Sen. Pat Roberts (R), one of the Senate’s most reliably anti-choice members, fights for his fourth Senate term.

Despite the efforts of Republican Secretary of State Kris Kobach, Democratic candidate Chad Taylor has been allowed to withdraw from the campaign and remove his name from the ballot, leaving Roberts up against Orman. Kobach had made efforts to keep Taylor’s name on the ballot in what many Kansas political observers saw as a ploy to split the anti-Roberts vote.

Roberts has trailed Orman in the polls since August, but Orman’s lead has narrowed in recent weeks.

Orman, while he has not spoken at length on the subject, has staked out a pro-choice position on reproductive rights. Orman believes that women must be trusted “to make decisions about their own reproductive health,” according to his campaign site. He’s also supportive of same-sex marriage.

Kansans for Life has criticized the judge’s ruling allowing the Democratic candidate to withdraw from the campaign. The National Right to Life Committee has been critical of Orman for his positions on reproductive rights, the Affordable Care Act, and the ACA’s birth control benefit.

Orman has never held public office, and has only once been a candidate. In 2008, he was a candidate in the Kansas U.S. Senate Democratic primary, but withdrew before the election. Orman is making his independence central to his campaign, but has been noncommittal to which party he may caucus with if elected.

Sen. John McCain has joined Roberts on the campaign trail, and the Kansas City Star reports that McCain said that if Orman “walks like a duck and he quacks like a duck, and he is a duck.” Speaking at the Johnson County Republican headquarters, McCain said, “We all know what he is. Let’s be honest. He’s a Democrat.”

Former Alaska Gov. Sarah Palin has also campaigned for Roberts and criticized Orman for being “wishy-washy, on the fence.”