The Associated Press:

Once a bright spot for President Barack Obama, North Carolina is now more like a political migraine less than four months before Democrats open the party's national convention in Charlotte.

... When Democrats announced the choice in February 2011, they said selecting the Southern city signaled Obama's intent to fight hard for the conservative-leaning state like he did in 2008. They also highlighted the economic transformation in the state and in Charlotte - from tobacco, textiles and furniture-making to research, energy and banking. Party leaders noted the state's strong political leadership and expressed hope that a Perdue re-election bid would get a boost from the attention that would be lavished on the convention.

Now traditional Democratic Party groups are threatening huge protests in part because they're deeply uncomfortable that the convention is being held in one of the least union-friendly states. And thousands of Democrats across the country are calling for the convention to be relocated because of the gay-marriage vote.

... There's also the fired-up Republican base that turned out Tuesday to approve the constitutional ban on gay marriage. The vote prompted more than 28,000 people to sign an online petition - by the New York-based Gay Marriage USA - to move the convention from Charlotte. Twitter also was flooded with similar sentiment from angry supporters of same-sex marriage. Obama stated his support for gay marriage a day after the vote.

Democrats want to include gay marriage in the platform to be adopted at the convention. That could create controversy at a gathering that's intended to promote party unity by drawing attention to a divisive social issue when the economy remains the most pressing concern.