Story highlights The act, passed overwhelmingly by the House, sanctions Iran for its support of terrorist organizations

It also grants the President the authority to levy additional sanctions on Tehran

(CNN) In a bid to secure the Iran nuclear deal before President Barack Obama leaves office, his administration is working to stave off any additional sanctions and encouraging American companies to do business with Iran, a US official told CNN.

The moves have already met with opposition on Capitol Hill with the Republican leadership in the House sending a letter Tuesday to Obama asking his administration to cease efforts to facilitate companies doing business with Iran during the transition period.

"We respectfully request that your administration take no further actions designed to bolster international investment in Iran," House Speaker Paul Ryan, Majority Leader Kevin McCarthy and Foreign Affairs Committee Chairman Ed Royce wrote.

"President-elect Trump deserves the opportunity to assess United States policy toward Iran without your administration imposing or implementing additional measures that could complicate the incoming administration's ability to develop its policy," they added.

A senior State Department official who is involved in the negotiations told CNN that there was "no specific effort to seal things irretrievably before the end of the term, rather just to keep meeting our commitments under the JCPOA," using the acronym for the accord.

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