Mukherjee spoke to Kumar a day after the Janata Dal-United declared its support for the UPA Presidential nominee.
The finance minister had also called JD-U chief Sharad Yadav on Thursday to thank him for extending support for his Presidential bid, JD-U sources said.
The JD-U had broken ranks with Opposition NDA on Thursday to declare its support for Mukherjee in the election for the top constitutional office.
