New Delhi: Nearly 20 to 25 per cent names may be deleted from Delhi's existing electoral rolls during the ongoing Special Intensive Revision (SIR), with election officials attributing the estimate to Delhi's highly mobile population, frequent transfers of government employees and people shifting homes without updating their voter registration. A senior official in the office of Delhi chief electoral officer said the figure is only a broad estimate and the actual number would become clear only when the draft electoral rolls are published on August 17. But the exact figure will emerge only after the draft rolls are published," the official told PTI on Thursday. In many cases, the voters have not necessarily left Delhi but have moved elsewhere in the city without transferring their enrolment. Deployed in New Delhi assembly constituency's Ansari Nagar area, BLO Manish Meena said his polling booth presents this very challenge.