In the two-page letter, he has congratulated Ajay Kumar Lallu and also the new Congress legislature party leader Aradhana Misra on their new responsibility.
"I personally wanted to be present to welcome you to your new responsibility in this festive season but due to unavoidable circumstances, I am unable to come to Lucknow," he said.
Babbar further said that with General Secretary Priyanka Gandhi Vadra at the helm of affairs, a new rush of energy in the party was palpable. "The formation of the new organisation gives a clear message that the party is ready for struggle and I am confident that the Congress will emerge stronger under her leadership," he wrote.
He further said that though he made all possible efforts to strengthen the Congress as UPCC President, he may have faltered at times because the party did not get the expected results.
Babbar said that from the smallest party workers to senior leaders, he received full cooperation from all and he will remain grateful to them for this.
"I may not have fulfilled the aspirations of some leaders and for this, seek forgiveness. The Congress is a party with a history and has strong roots in the country, especially in the rural areas. There is no denying the fact that the faith of the people in the party has been shaken but this is a temporary phase and there is no religion bigger than humanity," he said.
He gave his best wishes to the new UPCC team.
This is the first time in any political party that an outgoing office bearer has sent his wishes to the new team through a letter, copies of which have been sent to Congress President Sonia Gandhi and General Secretary Priyanka Gandhi Vadra.
"Raj Babbar has proved that he was the right choice for the party - only the time was wrong. His letter shows his magnanimity," said a senior office-bearer of the Babbar team.
( With inputs from IANS )