CANBERRA, Australia — Australia’s deputy prime minister warned Friday that the greatest threat to the U.S. economy are the “cranks and crazies” in the Republican Party, a rare foray into American domestic politics that was blasted by the opposition.

Wayne Swan, who also serves as treasurer and is his center-left Labor Party government’s ranking finance minister, took aim at the Tea Party during a speech to a business forum, breaking a convention among Australia’s major parties to steer clear of U.S. domestic political debates.

“Let’s be blunt and acknowledge the biggest threat to the world’s biggest economy are the cranks and crazies that have taken over a part of the Republican Party,” Swan said.

He said “the extreme right Tea Party wing” of the Republican Party had held the national interest hostage during last year’s debate over the U.S. borrowing limit despite President Barack Obama’s “goodwill and strong efforts.”

He said it was imperative that Congress reach an agreement to support growth and avoid a “fiscal cliff” of deep government spending cuts and higher taxes in January, which he said could push the U.S. economy back into recession.

The conservative opposition said Swan’s speech betrayed his “hatred” of Republicans.

“The Labor Party is peddling hatred and they’re got to stop,” opposition treasury spokesman Joe Hockey told reporters. “They hate the Republican Party. I’d like Wayne Swan to say something positive about someone somewhere.”

Prime Minister Julia Gillard, who travels to New York next week to address the United Nations General Assembly, defended her deputy’s comments as “appropriate.”

“What happens in the U.S. economy matters to the world economy and it matters to us,” she told reporters. “Wayne Swan was making that very common sense point today.”

Adam Lockyer, a lecturer at Sydney University’s U.S. Studies Center, described Swan’s speech as “a clumsy political move” that left him open to attack from his political enemies.

Lockyer said Swan might have been attempting to link the Tea Party to the obstructionism of the Australian opposition, which has thwarted Labor’s legislative agenda in a finely-balanced Parliament.

Australia has long maintained that its close relationship with Washington, and its 61-year-old defense alliance, remains strong regardless of who is in the White House.

Former conservative Prime Minister John Howard was widely criticized in 2007 when he claimed Obama, then a Democratic presidential nominee, represented al-Qaida’s interests.

Howard, a staunch U.S. ally in the Iraq war who lost elections later that year after 11 years in power, created one of the first controversies of Obama’s presidential campaign by attacking his plan to withdraw troops.