WASHINGTON —  An aide to President Bush has resigned because of his alleged misuse of grant money from the U.S. Agency for International Development when he worked for a Cuban democracy organization.

Felipe Sixto was promoted on March 1 as a special assistant to the president for intergovernmental affairs and stepped forward on March 20 to reveal his alleged wrongdoing and to resign, White House spokesman Scott Stanzel said Friday. He said Sixto took that step after learning that his former employer, the Center for a Free Cuba, was prepared to bring legal action against him.

Stanzel said the alleged wrongdoing involved the misuse of money when Sixto was an official at the center.

The matter has been turned over to the Justice Department for investigation, Stanzel said. He said Bush was briefed on the case and felt that the appropriate action was being taken.

The Center for a Free Cuba describes itself as an independent, nonpartisan institution dedicated to promoting human rights and a transition to democracy and the rule of law in Cuba.

Sixto joined the Office of Intergovernmental Affairs in July 2007 and was assigned to deal with state legislators, Native American groups and Hispanic officials on issues such as Cuba, Puerto Rico, health, labor, transportation, the environment and energy, Stanzel said.

"Mr. Sixto allegedly had a conflict of interest with the use of USAID funds by his former employer," Stanzel said. He said he did not know how much money was involved or the particulars of the allegations.

Sixto is the second White House aide to resign under a cloud in less than a month. Timothy Goeglein, who served as Bush's middleman with conservatives and Christian groups, resigned on Feb. 29 after admitting to plagiarism. Twenty columns he wrote for an Indiana newspaper were determined to have material copied from other sources without attribution.

Goeglein was a special assistant to Bush and deputy director of the Office of Public Liaison.