Mulford has impressed upon the diplomats that their countries should back the deal as it was in the interest of nuclear non proliferation system.
Mulford is understood to have stressed that India needed to be given exemption so that it can have nuclear trade with the international community.
Among the countries whose envoys he met are Britain and France.
India needs waiver from the 45-nation NSG by consensus to allow it to resume nuclear trade with the international community after about 34 years.
Under the Indo-US nuclear deal, Washington has promised to take up with the NSG India's case and push it through.
India's case will go to the NSG after the safeguards agreement between New Delhi and the IAEA is firmed up.
The safeguards agreement has already been reached and it is in the process of being approved by the Board of Governors of the 35-nation UN nuclear watchdog.