Barack Obama
Barack ObamaReuters

Leading members of Congress are pressing US President Barack Obama to abandon his attempts to force through a nuclear deal with Iran, after the deadline for talks was extended on Tuesday to July 7 in a last gasp week-long reprieve.

In response to the desperate efforts to reach a deal despite the obvious differences in position that continue to prevent an agreement from being reached, Senate Majority Leader Mitch McConnell (R-KY) blasted the Obama administration in an op-ed for Politico.

"President Obama and Secretary of State Kerry should use the opportunity to pause negotiations, take a step back and re-examine the point of the talks in the first place," said McConnell.

Differences between the two sides are apparent even in terms of the deadline; while the US announced an extension to next Tuesday, Iranian Foreign Minister Mohammad Javad Zarif said Wednesday "we did not set any deadline," reports Fox News.

Efforts to reach a deal on Iran's nuclear program continue Thursday, with International Atomic Energy Agency (IAEA) Chief Yukiya Amano visiting Tehran to try and get Iran to come clean on the military aspects on its nuclear program.

Meanwhile in Vienna, US Secretary of State John Kerry and Zarif are to be joined by the foreign ministers of France, Germany, Britain and China for a final push in negotiations.

US same as leading state terror sponsor?

A key sticking point in the talks has involved Iran's refusal to allow inspectors in to investigate its secretive nuclear facilities.

Top Republican senators lashed back after an anonymous administration official on Monday said inspectors shouldn't be able to inspect "every military site" in Iran, "because the United States of America wouldn't allow anybody to get into every military site."

Senators John McCain (R-AZ) and Lindsey Graham (R-SC) slammed the comment in a joint statement for its comparison of the US to the leading state sponsor of terrorism.

"With the Iranian nuclear negotiations in a critical phase, this statement should alarm us all," the two remarked. "There is no place in this negotiation for moral equivalence. That thinking was wrong in the Cold War, and it is wrong today. Iran is not like any other nation, least of all the United States. Iran has a proven record of cheating on its nuclear program."

House Foreign Affairs Committee Chairman Ed Royce (R-CA) also condemned the administration's stance, saying, "the standard needs to be 'go anywhere, anytime' - not go 'some places, sometimes.'"

Congress will have 30 days - or 60 if a deal is reached after July 9 - to review any nuclear deal, and can vote to block the sanctions relief.

However, experts have warned that the current sanctions regime against Iran has not been tough enough, allowing the Iranian GDP to grow 3% in 2014. Just this Monday Iranian officials announced that 13 tons of gold had been repatriated as part of sanctions relief, bringing the total in unfrozen assets since the November 2013 interim deal was signed to just under $12 billion.

Senior Iranian officials have gone on record saying that the Islamic regime will use advanced centrifuges after a deal is signed, a move which would allow it to obtain a nuclear arsenal within weeks.