A Democratic love-fest came to a screeching halt Friday after a high-ranking Hispanic party official abruptly resigned amid allegations he used a racial slur during a heated argument with a black aide to Democratic National Committee Chairman Howard Dean.

Alvaro Cifuentes was chairman of the DNC's Hispanic Caucus and is well-known in national Hispanic Democratic circles.

Cifuentes was attending the DNC's winter meeting in Washington, D.C., on Friday when he and the aide got into an argument.

It's not clear what started the fight, but sources said Cifuentes called the aide, who is black, "boy" twice during the confrontation, and two conference attendees were alarmed enough to try and restrain Cifuentes.

Sources said they believed Cifuentes' actions to be physically intimidating, and his words racially insensitive.

DNC spokeswoman Karen Finney confirmed the resignation Friday evening, saying it occurred after a meeting with Dean, the former governor of Vermont. She said that Cifuentes resigned his post as caucus chairman, but remains a member of the DNC.

Asked if Dean forced Cifuentes to resign his post, Finney said: "Gov. Dean and Alvaro had a private meeting this afternoon. Following that meeting, Alvaro attended the Hispanic Caucus meeting, [and] submitted his resignation. It was accepted by the caucus."

Attempts to reach Cifuentes for comment by phone were unsuccessful. His home phone number is restricted, according to phone company records.

A man who answered to the name "Alvaro" at a number believed to be the Cifuentes household said the caller had the wrong number before the reporter identified himself, and then hung up. Repeated phone calls to that number were not answered.

The Spanish-language newspaper El Nuevo Dia in San Juan, Puerto Rico, reported that Cifuentes sent an e-mail to the aide and caucus members Friday apologizing for the incident.

According to the e-mail obtained by the newspaper and described to FOXNews.com, Cifuentes wrote "it is proper to offer you my apologies," although he indicated that he might have mixed his words because he spent the majority of his life outside the United States in Puerto Rico. Cifuentes was born in Puerto Rico and also was chief of staff to a former governor there.

Sources said the argument appeared to stem from a dispute that began Thursday over how the 2008 Democratic convention in Denver was being planned. According to sources, Cifuentes didn't like Dean's moves to centralize power over the upcoming convention in the hands of those in Washington.

Dean's aide reportedly approached Cifuentes, telling him: "If you don't like his leadership, you can leave," sources who were near the confrontation recalled.

Finney said the party did not have any further response to Cifuentes' resignation, but another DNC source said "it was the right thing to do."

Cifuentes had been chairman of the Hispanic Caucus since 2001, Finney said. Caucus chairmen are voted upon by members in the caucus, which is made up of Hispanic members of the DNC. Caucus chairmen are not paid officers of the DNC, but they do sit on the party's decision-making executive committee. There are 447 total DNC members.

The resignation followed a spat between two other Democratic lawmakers earlier this week. Rep. Loretta Sanchez, D-Calif., resigned from the House Hispanic Caucus after what she said were inappropriate remarks by the caucus chairman, Rep. Joe Baca of California. She said friends told her that Baca called Sanchez a "whore."

Baca has denied making the comments.

FOX News' Carl Cameron and Greg Simmons contributed to this report.