I think you need a multi-solution here. One would be a statutory declaration as a primary piece of identification. Another would be providing the authority for election officials within a polling station to take an oath, and indeed take the oath without vouching. But if you're going to insist on vouching, you're going to have to expand the vouching system considerably, as Mr. Quail has referred to.
On November 28th, 2006. See this statement in context.