"The members of Parliament and the state Assemblies should take the call of their conscience and vote accordingly," Thakur, also a Rajya Sabha MP, told reporters.
Praising the BJP-backed presidential candidate P A Sangma, he said the former Lok Sabha speaker was a secular leader as well as reputed tribal leader.
Senior party leader Arun Kumar Sinha said Sangma will come to Bihar on a day-long visit on July 14 and attend a meeting with BJP legislators to solicit their support.