Bombadil: One of the Blue Wizards?

[Inziladun]

Alfirin has a good point.

Also, from the words of Elrond regarding Tom, I think a Bombadil-Istari connection unlikely.

'But I had forgotten Bombadil, if indeed this is still the same that walked the woods and hills long ago, and even then was older than the old.'

FOTR The Council of Elrond

Since the Istari had only come to Middle-earth in the Third Age, it's difficult to see one like Elrond, born in the latter part of the First Age, referring to one of the Wizards in that manner.

x/d with blantyr making a similar observation.