While Azad, Leader of Opposition in the Rajya Sabha, has been made in charge of Uttar Pradesh, Nath will look after Punjab and Haryana, party General Secretary Janaradan Dwivedi said.
Assembly elections in Uttar Pradesh and Punjab are scheduled early next year.
So far Madhusudan Mistry was looking after Uttar Pradesh and Shakeel Ahmed was taking care of Punjab and Haryana.
Sunday's appointments are being seen as a precursor to further restructuring of the AICC Secretariat.
The reshuffle came at a time when talk of Rahul Gandhi being elevated as party chief had again gained ground.
Sonia Gandhi effected the changes a day after the biennial elections to the Rajya Sabha which saw cross voting by some party MLAs in Uttar Pradesh and alleged deliberate faulty marking by its 14 legislators in Haryana which led to their votes being declared invalid and resulted in the defeat of Congress-backed candidate R K Anand. There were allegations of internal sabotage at the behest of former Haryana chief minister Bhupinder Singh Hooda.
Azad, 67, is a Gandhi family loyalist and a former Chief Minister of Jammu and Kashmir, while 69-year-old Nath is the seniormost MP in the current Lok Sabha having won from his pocket borough of Chhindwara nine times.
Azad was earlier twice the AICC General Secretary in charge of UP. Nath was a General Secretary some 15 years back in charge of key states like Gujarat and West Bengal.
His name was doing rounds as the possible new party chief in Madhya Pradesh.
Congress has roped in poll strategist Prashant Kishor, who successfully managed Prime Minister Narendra Modi's Lok Sabha campaign in 2014 and Bihar Chief Minister Nitish Kumar's last year, to aid and assist the party's UP and Haryana units.
In UP, Congress had secured just two seats in the last Lok Sabha elections with Sonia Gandhi and Rahul Gandhi emerging victorious from their traditional seats of Rae Bareli and Amethi.
The Congress is in political wilderness in UP since 1989 following emergence of divisive 'Mandal-Mandir' politics and rise of the BSP, which took away its crucial Dalit vote base.
In Punjab, Congress is in the opposition for the last nine years and is making a determined bid to capture power from SAD-BJP combine at a time when AAP has also come up as a serious contender for power.
The appointment of seasoned politicians like Azad and Nath came amid calls for a "major surgery" from within the party following its recent debacle in assembly polls in four states, including Assam and Kerala.
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