North Carolina is now one of the tightest states in the 2008 presidential election. Pollster.com shows Barack Obama with only a slight 2.2% edge over John McCain. Nate Silver's popular 538.com shows it even closer: By his analysis, Obama's lead is merely .4% -- making NC the tightest state in the country.

With North Carolina's critical 15 Electoral College votes likely to be decided by a razor-thin margin, there is growing concern the race could be affected by the state's use of confusing ballots that under-count tens of thousands of presidential votes each year.

Some background: North Carolina is one of only two states in the country where straight-ticket voting does not count a vote for president. For example, if someone marks the box to vote straight-ticket Republican -- but doesn't also tick off a vote for John McCain at the top of the ballot -- McCain won't get a vote.

The result is that every presidential election, North Carolina has an unusually high number of "undervotes" -- ballots that are cast but don't register a vote for president.

In 2000, more than 75,000 votes in North Carolina had no vote in the Bush/Gore presidential race. In 2004, the percentage of undervotes slightly declined, but the total number actually increased -- more than 92,000 ballots didn't register a vote for president.

Here's a chart by computer scientist Dr. Justin Moore at Duke University, using N.C. State Board of Elections data:
NORTH CAROLINA UNDERVOTE -- 2000 & 2004 ELECTIONS

Race / Turnout/ Votes for President / # of Undervote / % Undervote
2000 / 3,015,964 / 2,940,600 / 75,364 / 3.15
2004 / 3,593,323 / 3,501,007 / 92,316 / 2.57
Some undervotes are intentional -- voters who don't like any of the presidential candidates leave it blank on purpose. Some undervotes can also be chalked up to voting machine errors, since undervotes are somewhat different depending on how votes are counted.

But the fact that North Carolina has one of the five highest undervote rates in the country -- the national average was under 2% in 2000 -- makes it clear the state's confusing straight-ticket ballots are a leading factor. An in-depth report on the undervote problem in 2004 by Thomas Hargrove of Scripps Howard News Service concluded:
Both North Carolina and South Carolina historically suffer unusually high undervotes in presidential elections because, by state law, voters who mark the "straight-party-ticket voting" option must also vote separately for president. Every four years, tens of thousands of voters in both states apparently forget to do this.
Indeed, after the high 2004 undervote, the head of the N.C. State Board of Elections agreed the state's confusing ballots were to blame:
Gary Bartlett, executive director of the North Carolina Board of Elections, did not defend the high undervote or suggest voters are ignoring the presidential race. "I was hoping we would improve over what happened in 2000. But this shows a law in our state that needs to be reviewed and probably be changed," Bartlett said.
What kind of impact could this have in 2008? A lot.

Consider the following: Right now, 538.com projects that Barack Obama is at 49.5% in North Carolina and John McCain at 49.1%. Given that there are just under 6.2 million voters currently registered in North Carolina -- and assuming N.C. voter turnout surpasses the 1984 high-water mark and reaches 70% in 2008 -- some 4.3 million votes will be cast this year.

Using current projections, that means the current difference between McCain and Obama is under 17,300 votes in North Carolina -- that's less than a fifth of the 92,000 presidential undervote in 2004.

The Obama campaign is especially concerned, since new voters -- which the campaign has worked so diligently to register -- unfamiliar with the law will be most affected. Anecdotal evidence is already rolling in that many Obama voters are not having their vote for president counted. For example, a diarist at DailyKos yesterday made this report:
My mother has been working the polls in North Carolina for early voting and has alerted me to something that I think would be important for NC voters to know. If you circle in the choice for a straight Democratic ticket (or republican for that matter), you ARE NOT casting a vote for the presidential race - you MUST fill that in separately.

She says that in the last few days alone, she has personally seen at least 200 votes intended to go to Obama that were not being counted (in other words, people telling her how excited they are to see Obama elected, only to find out that by selecting the straight democratic line, they never even cast a vote for him).
Some Democrats are using creative measures to counter the confusion. For example, Democrats in Durham County are promoting the "Obama - Straight - Flip," complete with amusing YouTube video.