Calls for a better presidential transition next fall are a cottage industry in Washington, and for good reason: The next president must hit the ground running.

Unless their transition planning is so secret that it has yet to leak out — which is hard to believe — Sens. John McCain and Barack Obama are already late on this important task. Done well and acknowledged publicly, transition planning reassures voters that the candidates are serious about governing. Done in secret, voters can only assume that the winner will wake up on Nov. 5 in a Robert Redford moment, asking "What do we do now?"

There are many reasons why the two candidates might postpone transition planning. Obama was in a tight primary contest that took him into June, while McCain has been desperately trying to weld together a campaign machine for months. It's not unusual that both would want to avoid the real distractions of getting too far ahead of themselves, or would be loath to spend hard-earned campaign dollars or a nanosecond of time on the details of a transition that may never occur.

Perhaps most important, the candidates are worried about how it would look to the public. The front-runner (Obama for now) cannot announce that he has begun a transition plan without being accused of hubris, while the underdog (McCain) cannot make such an announcement without raising questions about his sanity.

Nevertheless, the arguments for detailed and publicly acknowledged pre-convention transition planning are overwhelming. This is a situation in which the plane cannot be built while flying it.

For starters, the presidential appointments process has become a nightmare of endless vetting that creates long vacancies once the president is inaugurated. Whereas John F. Kennedy's first round of roughly 200 Senate-confirmed appointees was in office by late spring in Year 1, George W. Bush's class of almost 600 was not fully in place until late spring in Year 2.

The challenge is not just in the sheer number of appointees who have to be cleared for nomination and confirmation. It is also in completing 60-plus pages of forms. One of the first things potential nominees need to do is dig out their high school yearbooks and identify someone, anyone, who can vouch for them when the FBI comes calling. One of the next is providing the reason for every foreign trip, Canada and Mexico included, taken over the last 15 years.

Pre-convention transition planning involves more than preparing for the appointments process. President Clinton symbolically announced new ethics rules for his appointees on inauguration day, but early transition planning could go much further, establishing immediate priorities about the legislative agenda, budget revisions, pending regulations and executive orders.

Most important, transition planning now would allow the president-elect to concentrate his political capital on the first year.

Instead of waiting for Labor Day or later, Obama and McCain should jointly announce their commitment to transition planning now.

A joint announcement on transition planning would accomplish three ends. First, it would insulate both campaigns from the counting-chickens criticism.

Second, pre-convention planning would allow the campaigns to create a master list of the top jobs they will need to fill first. The transition team should ask potential candidates to fill out their forms before election day, then Bush should issue an executive order allowing the FBI and the Office of Government Ethics to begin the background checks on Nov. 5.

Third, pre-convention transition planning would allow the presidential candidates to start deepening their expertise for the first 100 days in office.

Obama and McCain would hardly be the first candidates to think about the transition before their party conventions. Ronald Reagan's transition planning was early and disciplined, which contributed greatly to his early victories on tax and budget cuts, while Clinton's was late and messy, which played no small role in the national health insurance debacle and the Republican takeover of Congress in 1994.

An open commitment to pre-convention transition planning would would set a precedent for future campaigns. It would be the biggest favor they could do for future candidates and appointees. It also would be a salutary gesture toward governing.

Paul C. Light is the author of "A Government Ill Executed." He wrote this commentary for the Los Angeles Times.