The influential rights group Mothers of the Plaza de Mayo is struggling with a corruption scandal that forced it to fire a top executive accused of misusing taxpayer funds meant to build housing for the poor.

The group is a close ally of Argentina's presidency and the scandal could have political consequences with only months to go before the Oct. 23 election. President Cristina Fernández enjoys a wide lead in the polls and is favored to win re-election should she announce her candidacy this month.

The judicial investigation has already been broadened to include any politicians and government appointees found to be involved in the scandal.

"If there wasn't complicity, there was negligence in terms of government controls. This case is yet more proof that the controls aren't working in Argentina," Ricardo Alfonsin, the president's leading challenger, said in an interview he promoted on Twitter.

On Wednesday, opposition members of Congress called for more transparency and controls in government spending, and governing party deputies defended the Mothers group as key to the president's populist programs.

The human rights group began during the 1976-83 dictatorship when its founders demanded information about their children who had disappeared in the military junta's campaign to eliminate political dissenters. In recent years, the group has evolved into a political movement that backs specific candidates and unions, is a fixture at governing party rallies, and runs a wide range of social programs as well as radio and television stations.

Since 2008, the government has given the Mothers group about $187 million for more than 2,000 housing and related construction sites, Deputy Public Works secretary Abel Fatala told a congressional committee Wednesday. But he insisted that local officials, not the federal government, were responsible for making sure the money was properly spent.

Opposition leaders said the Mothers and federal officials showed a shocking failure of responsibility.

Fernanda Reyes, a deputy with the opposition Civic Coalition, said that since 2004, only 35 percent of housing that should have been built with taxpayer money was actually finished. A Peronist party deputy, Gustavo Ferrari, countered that the Mothers group is now Argentina's second-biggest housing builder in terms of the number of people it employs.

Sergio Schoklender, the right hand of the Mothers' president, Hebe de Bonafini, is accused along with his brother Pablo and more than a dozen others of fraud, money laundering and illegal enrichment. Sergio Schoklender served as the rights group's legal representative, which gave him key financial and administrative responsibilities.

Prosecutor Jorge Di Lello's complaint alleges Schoklender made a series of suspicious operations that shifted taxpayer funds into businesses he owns.

While earning about $16,000 a year to help Argentina's poor, Schoklender amassed a 19-room mansion, Ferrari and Porsche sports cars and a yacht, according to the opposition Clarin newspaper. Schocklender also frequently flew around the country in private jets, the paper said.

Judge Norberto Oyarbide has barred the Schoklender brothers from leaving Argentina and ordered a series of raids to recover documents. At one point, Sergio Schoklender showed up unexpectedly at court to give the judge evidence such as receipts, bank statements and other financial documents that he said would prove he committed no crimes, according to his lawyer, Adrian Tenca.

The government, meanwhile, has moved forcefully to support Bonafini and fix any blame on those who worked for her.

Bonafini, who visited the presidential palace Wednesday, is seeking to distance herself from the Schoklenders, whom she had treated like sons. She founded the group after her own two sons disappeared during the military dictatorship and long defended the Schoklenders, who were released early from life terms in prison after killing their parents in a 1981 crime that shocked Argentina.

"I'm neither the first nor the last mother whose son gets into big trouble," Bonafini told the pro-government Tiempo Argentino on Sunday in an interview that set the tone for this week's wagon-circling. "The accusations are against the legal representative, who was Sergio, and against his brother, and if they committed crimes they will have to pay."

The formal complaint doesn't directly target the Mothers group but raises questions about its activities and the conduct of government officials who directed millions of dollars to its public works projects, apparently without enough controls.

The case has drawn criticism from some of the group's traditional allies, such as Adolfo Perez Esquivel, who was imprisoned by the dictatorship for his human rights work and won the 1980 Nobel Peace Prize for drawing attention to the junta's abuses and condemning political violence.

"I believe there's a great responsibility on the part of the government to determine the controls, audits, submission of receipts, because this doesn't involve pocket change — it's millions and millions of pesos," Perez Esquivel said.

He also questioned the Mothers group for going beyond its traditional mandate to get involved in pro-government political causes. Another group, the Grandmothers of the Plaza de Mayo, also is a close supporter of Fernández, but remains more focused on its core mission of seeking justice for the dictatorship's human rights victims.

Fernández's Cabinet chief, Anibal Fernández, argued in his weekly opinion column that opponents will try to use the scandal to justify a frontal attack on human rights gains in Argentina.

"What's done is done and you have to investigate it," he wrote. "But they're trying to blame the heart of the human rights groups."

This story is based on The Associated Press reporting.