The Democrats may be about to open Pandora’s box with their latest effort to revamp the presidential primary schedule.

A party commission is studying how to expand the number of states with meaningful contests beyond the two that start the process, Iowa and New Hampshire.

But the whole thing could blow up if it leads to too many early contests. That could increase the advantage to the best-known, best-financed candidates, reduce further the chance for an unknown to emerge and prevent the scrutiny the system should provide.

This is at least the sixth party panel to tackle the nominating system. It is reportedly considering letting two to four states with diverse populations hold contests between the Iowa caucuses and the New Hampshire primary.

But there’s no guarantee the proposed solution will have the desired effect without producing other, unintended results. That’s happened each time either party has tried to “fix” the process. I can say that with some authority because I’ve covered this subject ever since the first Democratic ad hoc reform panel in 1968.

That’s when Sens. Robert Kennedy and Eugene McCarthy led a revolt against the Democratic establishment and discovered the rules were rigged against them; that is, where there were rules.

The reformers convinced the 1968 Democratic convention to create a commission to fix things. Led by future presidential candidate George McGovern, it wrote detailed rules of what could and could not be done.

As a result, many states adopted primaries as the easiest way to meet the new rules, which said the results should reflect voter preferences and expanded the roles of women, minorities and youths.

For several elections, this created exciting, competitive contests that lasted from March until June and provided an obstacle course that tested the candidates.

It also reduced the role in presidential politics of top Democratic politicians, leading to the election of Jimmy Carter, whose effectiveness suffered because he had minimal ties to party leaders. Later changes restored their role. By then, various states decided to increase their influence with ever-earlier caucuses or primaries.

In 2000, the Republicans voted to add more February contests in hopes of reducing the role of New Hampshire, where a state law requires the primary to be held at least one week ahead of any other.

That produced an exciting GOP race for several weeks until George W. Bush dispatched the challenge of Sen. John McCain. But in 2004, it led to seven Democratic primaries a week after New Hampshire. The result: a battle of TV ads that merely ratified Iowa and New Hampshire.

Opening up the calendar further poses two main dangers. A big state like Michigan – the main force behind this commission – might try to move to the top of the calendar, making it difficult for all but the best-known, best-funded candidates to compete. And so many states may hold early contests that the only way to campaign will be on television and airport tarmacs.

That would be unfortunate. Though Iowa and New Hampshire are unrepresentative states with mainly white populations, they have serious voters who test the candidates by scrutinizing their backgrounds and views. That scrutiny led to the collapse of Howard Dean’s candidacy in 2004.

Early tests in other small states could play a similar role. But replacing their role with either a single large state or a multiplicity of contests will only help candidates hide behind their commercials and avoid voters’ questions.

It will also make it virtually impossible to stop the front-runners.

Any changes the Democratic panel votes next month could trigger months of wrangling. New Hampshire Democrats will resist putting more states before their primary; they would put two small states with substantial minority populations after Iowa and New Hampshire, before anyone else.

Any Democratic change could also change the GOP calendar. But it would not likely change the fact that front-runners generally win.

Since reforms started in 1972, Republicans have always picked the candidate who led the polls at the start of the election year. Democrats had done so since 1976 until Mr. Dean’s collapse enabled John Kerry to win in 2004.

Regardless of the rules, history says McCain, or former New York Mayor Rudy Giuliani, and Sen. Hillary Rodham Clinton will be favored in 2008 – if they run. Still, the country will be better off if they and their foes have to negotiate the rigors an extended schedule of contests would provide.

– Carl P. Leubsdorf is Washington bureau chief of the Dallas Morning News.