Patil, who had represented the Bhiwandi Assembly constituency, was welcomed into the party fold by Chavan and MPCC chief Manikrao Thakre.
Dalit leaders Jogendra Kawade of People's Republican Party (PRP) and former minister Sulekha Kumbhare also announced their support to the Congress-led Democratic Front in the state for the ensuing Lok Sabha elections.
To a query, Kawade said he had decided to back Congress to thwart "communal forces" from coming to power in Delhi.
In a veiled attack on RPI chief Ramdas Athawale, who is part of the Shiv Sena-BJP led opposition alliance, Kawade said, "How can people who call themselves followers of Babasaheb Ambedkar go with parties which opposed renaming of Marathwada University."
"These people (Athawale) go along with parties which have the likes of Arun Shourie who insulted Ambedkar in his book," Kawade said.
Meanwhile, responding to Kawade's criticism, Athawale said the Congress had roped him to woo Dalit voters.