The election of a new Speaker will put Parliament centre stage on Monday. If Parliament proceeds with the election using existing rules, it will diminish itself. For the public will see their own elected representatives incapable of organising a fair election among themselves. The plain fact is that the existing rules for electing a Speaker were designed for a bygone era of "emerging candidates" and political fixes. They should go.

The election of a new Speaker will put Parliament centre stage on Monday. If Parliament proceeds with the election using existing rules, it will diminish itself. For the public will see their own elected representatives incapable of organising a fair election among themselves. The plain fact is that the existing rules for electing a Speaker were designed for a bygone era of "emerging candidates" and political fixes. They should go.

These rules have developed from a centuries' old procedure intended to do no more than ratify the nomination of a Speaker already agreed in behind-the-scenes negotiations between the political parties. Indeed, the procedure committee of the Commons confirmed this in 1996 when, in concluding that the existing rules did not need changing, they said: "the onus is plainly on the parties concerned to agree on their favoured candidate..."

But this time there has, so far, been no "fix", at least as far as I am aware. We are faced with a novel situation - democracy is breaking out in the Commons and it looks as if there could be up to a dozen or more candidates to choose from but no sensible rules on how to choose between them.

The existing rules provide only for the Father of the House (Sir Edward Heath) to call on a Member to move a motion proposing a candidate and then for him to allow amendments backing other candidates to be debated and voted upon. As soon as any candidate proposed in an amendment secures a simple majority of Members voting, no matter how small that majority may be, and even if huge numbers of MPs abstain, the main motion, as amended, is then put to the House. If that candidate is then accepted, with or without a division, he or she is elected.

Such a system works with a couple of candidates but it creaks with a field of a dozen or more. Its shortcomings are legion. There may be many candidates who could secure a simple majority but the candidate commanding the strongest support might never even have the chance to be considered.

Conceivably, and even worse, in a large field with divided support, no candidate may secure a majority. This is uncharted territory for the House, for which the existing procedural rules make no provision whatsoever.

Many MPs are already well aware of the dangers and a flurry of letters is circulating among colleagues about it. Some of them are also encouraging me to support their candidates, but even a number of those actively campaigning have been unsure exactly what the rules are - as have I.

Clearly, we need some commonsense improvements to the rules. Tony Benn has suggested a ballot, giving MPs the opportunity to choose between all the candidates, followed by a play off between the top two. I urge colleagues to support Tony Benn's proposals and the Father of the House to allow them to be debated. He should certainly not be deflected by recondite concerns that such a debate might possibly contravene Standing Orders - they probably don't, in any case.

Enthusiasts for electoral systems may be able to polish his proposals but they are already sensible enough. Further refinement should come after this election, perhaps drawing on the experience of the devolved Parliament and Assemblies that have created similar ballot systems.

But we should not wait until after this election to change the rules. Democratising them now would not only give us the best chance of finding a Speaker who can command the support of the House. It would also remove the danger that after the election, the Procedure Committee would end up reluctant to recommend reform lest, in doing so, they undermined the legitimacy of the new incumbent.

As it happens, I myself am supporting Sir George Young, a man with huge parliamentary experience and who is capable of taking the House on what should be a gradual but steady reforming path in the 21st century. Others have their own preferred candidates: it is a reflection of the unacceptability of the current system that many of us may not have the chance even to register a vote in favour of them on Monday.

There is more at stake here than electing a presiding officer. Parliament needs to shore up its battered reputation and demonstrate that it is not just an inward-looking club operating according to arcane rules. The election of the Speaker is not an internal matter but a signal for the way decisions should be taken in a modern democracy. The major political parties have both felt the need to open up their own leadership elections to greater public scrutiny; so should the Commons.

Democratising the Speakership can also play at least a modest part in helping to revive Parliament.

Parliament's decline has many causes: the media is supplanting it as the main forum of political debate; it is too weak to prevent the calculated absenteeism of an increasingly presidential Prime Minister, our antiquated working methods leave too much of the Executive and its legislation unscrutinised; the Courts and Europe are bypassing it; the Lords is being transformed into a consultative quango appointed from Number 10, among much else.

But if the Commons cannot elect its own presiding officer fairly, it cannot expect the public to support it in its wider efforts to revive itself, and without that support Parliament will have no chance against an overmighty executive.

Andrew Tyrie is Conservative MP for Chichester