GPP president Gordhan Zadaphia, joined by party supporters, announced the merger at the BJP headquarters here.
The GPP took the call, much on the predictable lines, even as former chief minister and one of its founder members, Suresh Mehta, had opposed the move.
Terming the merger illegal and a unilateral call on the part of Zadaphia, Mehta said he would continue his fight against Modi.
GPP was formed ahead of Assembly polls by BJP dissidents and former CMs Keshubhai Patel and Suresh Mehta, along with Gordhan Zadaphia, then a junior home minister in the Modi cabinet.
Zadaphia insisted that the decision to rejoin BJP was taken through consensus.
"BJP is our alma mater and this decision of merger has been taken unanimously in presence of all district presidents and secretaries of GPP. The decision is taken considering the future of GPP workers, and to serve the nation. We all wish that Narendrabhai becomes prime minister," the GPP president said.
"There will be a official function when top state leaders including Narendra Modi will welcome GPP members at a function tomorrow," said BJP spokesperson Harshad Patel.
