Local Schools Information, the local authority funded advisory body, said there would not enough time for schools to get a decision on grant-maintained status from the Secretary of State this side of the election.
It said the GM process took a minimum of six weeks from deciding to hold a ballot.
If the vote was for opting out, proposals could be published within days but there was then a two month statutory period for objections before the Education and Employment Secretary could consider the matter.
On past experience Gillian Shephard's decision has seldom taken less than another couple of months and if it appeared that she had reached a decision hastily she could lay herself open to a legal challenge.
Political pundits claim that the most likely dates for the general election are April 10 and May 1.
Martin Rogers of LSI said he now expected the trickle of ballots on GMS to stop and added: "This could well be the unofficial end of opting out."
The latest edition of LSI's leaflet Opting for What? urges parents asked to vote on opting out this term to question why and whether those responsible for holding the ballot really understand what they were doing.
It warns: "It is potentially a very divisive process and is certainly a distraction from a school's real purpose of educating children. Now, it may well also be pointless."
So far the Government has spent almost Pounds 8 million promoting opting out and it is now a statutory duty for governing bodies to consider every year whether to hold a ballot.
However, fewer than 0.5 per cent of eligible schools decided to do so last year - and half voted against opting out.