The incoming US national security adviser has dismissed claims that the surveillance whistleblower Edward Snowden has weakened the president, Barack Obama, and damaged American foreign policy.

Susan Rice, the outgoing US ambassador to the United Nations, said it was too soon to judge whether there would be any long-term repercussions from the intelligence leaks by the former National Security Agency contractor, which were published by the Guardian.

Rice rejected suggestions that Snowden's disclosures had made Obama a lame duck, damaged his political base and hurt US foreign policy, saying: "I think that's bunk."

"I don't think the diplomatic consequences, at least as they are foreseeable now, are that significant," she added.

"I think the United States of America is and will remain the most influential, powerful and important country in the world, the largest economy, and the largest military, [with] a network of alliances, values that are universally respected."

Chuck Hagel, the defence secretary, and General Martin Dempsey, the chairman of the joint chiefs of staff, have called Snowden's leaks a serious breach that damaged national security. Hagel said on Thursday an assessment of the damage was under way.

"There will always be difficult issues of the day and frankly this period is not particularly unique," Rice said. "I think the Snowden thing is obviously something that we will get through, as we've gotten through all the issues like this in the past."

The US has charged Snowden with espionage and demanded his extradition, but Hong Kong said the request was legally flawed and let him fly to Moscow and the Russians have so far refused.

Rice's comments came after it emerged on Friday that the plan to spirit Snowden to sanctuary in Latin America appeared to be unravelling, amid tension between Ecuador's government and Julian Assange, the founder of WikiLeaks, who is holed up in the country's London embassy.

The president, Rafael Correa, halted an effort to help Snowden leave Russia amid concern that Assange was usurping the role of the Ecuadoran government, according to leaked diplomatic correspondence obtained by the Spanish-language broadcaster Univision and shared with the Wall Street Journal.

Correa declared that the safe conduct pass issued by Ecuador's London consul – in collaboration with Assange – was unauthorised, after other Ecuadorean diplomats privately said the WikiLeaks founder could be perceived as "running the show".

Amid signs Quito was cooling with Snowden and irritated with Assange, Correa declared invalid a temporary travel document which could have helped extract Snowden from his reported location in Moscow.