RALEIGH, N.C. — President Barack Obama is speaking out against an amendment on the May 8 ballot that would define marriage in North Carolina as being between one man and one woman.

The Obama campaign issued a statement Friday, calling the proposed amendment discriminatory.

“While the president does not weigh in on every single ballot measure in every state, the record is clear that the president has long opposed divisive and discriminatory efforts to deny rights and benefits to same sex couples," campaign spokesman Cameron French said in the statement. "That’s what the North Carolina ballot initiative would do – it would single out and discriminate against committed gay and lesbian couples – and that’s why the president does not support it.”

Although North Carolina law prohibits same-sex couples from marrying, it is the only state in the Southeast without such restrictions written into its constitution.

Supporters of the referendum, which will be printed on the ballot as Amendment One, say marriage is not a right, and the amendment would protect the traditional institution of marriage from court rulings allowing same-sex couples to wed.

"President Obama has no business inserting himself into the people's business in North Carolina, said Tami Fitzgerald, chairwoman of Vote FOR Marriage NC, a coalition supporting the amendment. "The people of North Carolina cannot sit by and let marriage as the union of one man and one woman be destroyed by a handful of political activists or by activist judges."

Opponents of the measure say it would enshrine discrimination in the state's constitution and could have unforeseen consequences in other aspects of law including domestic violence protection orders, which supporters deny.

About 300 people marched through Raleigh to the State Capitol on Thursday to express opposition to the amendment.

The Human Rights Campaign – a national lesbian, gay, bisexual and transgender civil rights organization – praised Obama's stance.

“The president has made clear the importance of protecting all families,” HRC President Joe Solmonese said in a statement. “Amendment One undermines basic human dignity and places families of all types at risk in North Carolina. Voting 'No' on Amendment One is critical for maintaining a fair North Carolina.”

Obama narrowly won North Carolina in 2008, and the Democratic Party has made a repeat victory here a top priority. The party will hold its presidential convention in Charlotte in September.