Former U.S. president Jimmy Carter has issued a blistering indictment of the American electoral process, saying it is shot through with "financial corruption" that threatens democracy.

Speaking at the international human rights centre that bears his name, Carter said "we have one of the worst election processes in the world right in the United States of America, and it's almost entirely because of the excessive influx of money."

The dynamic is fed, Carter said, by an income tax code that exacerbates the gap between the wealthiest Americans and the rest of the electorate, allowing the rich even greater influence over public discourse and electioneering.

The 39th president lamented a recent U.S. Supreme Court decision that allows unlimited contributions to third-party groups that don't have to disclose their donors.

He added that he hopes the "Supreme Court will reverse that stupid ruling," referring to the case known as Citizens United.

Carter praised Mexico and several countries where staff at his centre have monitored publicly financed elections, and he said the United States should return to publicly financed elections for president. The system technically is still in place, but it is voluntary and both President Barack Obama and Republican challenger Mitt Romney have chosen to bypass the taxpayer money because they can amass far more on their own.

"You know how much I raised to run against Gerald Ford? Zero," Carter said, referring to his 1976 general election opponent. "You know how much I raised to run against Ronald Reagan? Zero. You know how much will be raised this year by all presidential, Senate and House campaigns? $6 billion. That's 6,000 millions."

The 87-year-old Carter and his wife, Rosalynn, appeared at The Carter Center to deliver a report on their human rights and public health initiatives around the world. They took questions from those in attendance and online viewers watching a webcast.

U.S. Has "Less Influence" in Middle East

Carter, a Democrat who left office in 1981, held forth on a range of foreign policy matters, nearly all of them situations where The Carter Center and the former president himself have been involved.

The United States, Carter said, has "less influence" over Middle East nations and diplomacy in that region than it has had at any time since Israel was established as a nation-state in 1948. "Our country's government has basically abandoned the effort," Carter said, adding that he still supports a two-state solution.

He said he hopes Israel resists any urge to strike Iran "on its own," and he discouraged President Obama from drawing a "line in the sand" that Iran would almost certainly cross.

In Syria, Carter said the civil war will worsen as other nations in the region flood the participants with weapons. "There is little hope of good things coming out of Syria any time soon," he said.

He praised the Venezuelan election process. He described a touch-screen voting system that immediately records a vote in a centralized location, while also printing out a ballot receipt that allows a voter to check the accuracy of the vote. He noted "criticism of the outcome" of recent elections there but said President Hugo Chavez won "fairly and squarely."

While the former president clearly relishes the detailed discussions of world political affairs, he and his wife emphasized that the centre's public health programs have had the greatest individual effects of their post-White House work.

Rosalynn Carter, who concentrates much of her work on mental health access and education, highlighted an ongoing effort to educate mental health professionals in Liberia. After three years of Carter Center involvement, three classes of nurses and other medical professionals have received advanced training in treating behavioural health concerns. The former first lady said the need is acute in the war-torn nation, which had just one practicing psychiatrist three years ago.