Republicans have plenty of reasons to dislike Obamacare already, but they haven't focused on one that could affect them in 2014 and beyond: anyone signing up for insurance under the Affordable Care Act will also have a chance to register to vote.

Before folks start accusing Democrats of engaging in a vast left-wing conspiracy, it's worth noting this quirk stems from the National Voter Registration Act of 1993 (better known as the "Motor Voter" law, because it allowed all Americans to register to vote while renewing their driver's license).

According to Centers for Medicare and Medicaid Services spokesman Brian Cook, applications in the insurance marketplace must include the offer of voter registration because the law "requires states to offer voter registration [at] all offices that provide 'public assistance' (including Medicaid applications). Because people applying on could be eligible for either Medicaid or Marketplace coverage, we will be providing info on voter registration to people who request it."

Could this give Democrats a political advantage? Potentially, since they stand to benefit the most from a surge in voter registration among those who currently lack insurance. By more than a 2 to 1 ratio, uninsured Americans supported Barack Obama over Republican Mitt Romney in a Washington Post-Kaiser Family Foundation poll last summer (62 to 27 percent). Obama led by a smaller eight-point margin among those who have health insurance. African Americans and Hispanics make up roughly half of the nation's uninsured, a factor that explains much of the political divide.

Take a look at this chart, which gives a sense of the disparity in voting patterns between the insured and uninsured:

But the impact of the voter registration option will also be limited by two key factors. Fully one in five of the nation's uninsured are not U.S. citizens, making them ineligible to vote at all, a factor that helps explain why the Post-Kaiser poll found just 64 percent of uninsured respondents are registered, 22 points below the national average.

Second, making voter registration easier doesn't always result in a boost in turnout. The same law that accounts for why Obamacare now presents a voting registration opportunity had only mixed effects on turnout after it was enacted. Turnout increased by roughly five percentage points in states that used combined forms for the DMV and voter registration or actively encouraged registration, wrote Political Scientist Benjamin Highton in a 2004 article summarizing research about the law. But in states that made less of an effort, turnout hardly moved.

Perhaps that explains why this development, which was first reported by Mother Jones on Tuesday, has not become a new rallying cry in conservatives' efforts to overturn the president's health care law.

“We are less concerned with the voter registration element of the enrollment application, and more concerned about defunding the law or at least getting a delay in the individual mandate," wrote Dean Clancey, director of policy for the conservative group FreedomWorks, in an e-mail. "Regardless of what’s on the enrollment application, the greater point is that enrollment in ObamaCare should be voluntary. Give Americans a choice.”