AIMIM decided to support Kumar at a meeting chaired by Asaduddin Owaisi last week, the sources said.
"Ten lawmakers of AIMIM are likely to vote for Meira Kumar," they said, adding that Congress president Sonia Gandhi and Telangana Congress leaders had spoken to AIMIM chief Owaisi, seeking his party's support.
Also, the AIMIM is most likely to vote for the opposition's candidate Gopalkrishna Gandhi in the election for the vice-president's post, they said.
NDA nominee Ram Nath Kovind is pitted against opposition candidate Meira Kumar in tomorrow's election for the country's top political office.