Sources in JPC said a questionnaire to the two "cannot be ruled out" though the Committee is yet to decide whom to call as a witness out of the 107 names it has.
The idea assumes significance as BJP and Congress members clashed at the JPC meet today over calling Singh and Chidambaram before the committee.
BJP, which has been insisting that they should be called, today stormed out of the meeting. Congress is resisting any such move.
After the meeting, JPC Chairman P C Chacko said one method is to summon witnesses while the other is to send them questions in writing to save time.
Asked whether the PM and the Finance Minister could be sent written questionnaire, Chacko said no decision has been taken so far on a fresh list of witnesses.
Chacko today circulated a draft list of 107 persons, including Manmohan Singh and Chidambaram besides BJP leaders Sushma Swaraj and Arun Shourie, for finalisation.
Chacko, who is eager to submit the report by December, wants to prune the list of witnesses to speed up the process of the JPC.
The BJP members insisted that it was necessary to call Singh and Chidambaram for a "fair investigation" into the 2G spectrum allocation scam of 2008.
