According to the sources, the BJP's state unit had requested the prime minister to address at least 20 more rallies in each of the 19 sub-divisions but Modi gave his nod to 10 rallies, citing prior engagements.
Read more: Bihar Elections 2015: Special Coverage
"The venues of the rallies will soon be finalised," a source said.
Modi has already addressed four rallies in Bihar.
The sources also said the BJP was willing to release a vision document in place of manifesto, as its president Amit Shah was of the view that manifesto was moral binding on the party whereas the vision document was a short and broad policy outline that gives certain amount of flexibility to decide the agenda of governance.
Polling for 243 assembly constituencies in Bihar will take place in five phases between October 12 and November 5, with the counting slated for November 8.