A survey conducted by NBC News has found that 68 percent of Americans do not believe Iran will uphold its part of a final nuclear accord with six major powers. 

Iran and the P5+1 countries – the US, China, Russia, France, Great Britain and Germany – reached a framework deal with Tehran in Lausanne earlier this month, which framed the parameters of a larger, more technical agreement due by June 30.

A quarter of those surveyed in the NBC poll, which was conducted online April 6-8 and released on Thursday, said they trusted the Islamic Republic "to abide by a nuclear agreement."

Under the pact, cast as an "understanding," Iran will be allowed to continue the enrichment of uranium and will close no facilities.

53% of respondents said Iran's nuclear program constitutes a major threat to the United States. 37%, by comparison, said it was a minor threat, while 8% said it was no risk whatsoever. 

Also, half said they were following events unfolding throughout the nuclear talks quite closely, with more Republicans than Democrats staying tuned to news coming out of Switzerland.

The American TV network also asked participants who they trusted more to spearhead negotiations to curb Iran's nuclear program – US President Barack Obama or the Republicans in Congress – to which most (54%) returned with support for the president. 

Nearly two thirds of the 2,052 adults surveyed said they felt the country was heading in the wrong direction. As for Obama's job approval ratings – the poll, which was done in conjunction with SurveyMonkey, found that some 51% of Americans approved of "the way Barack Obama is handling his job as president" compared to 48% who disapproved. 

World powers and Iran have yet to agree on a fundamental component of the structure of a nuclear deal, with the main disagreement between the parties being how to couple international sanctions relief for Tehran with its demonstrated compliance with an accord.

The United States and its allies want to lift sanctions over time, providing little relief up front, whereas Iran wants full exemption from all EU and UN sanctions upon the initial implementation of a comprehensive agreement.