Michael E. Toner, the chairman of the Federal Election Commission, has some friendly advice for presidential candidates who plan to be taken seriously by the time nominating contests start in early 2008: Bring your wallet.

"There is a growing sense that there is going to be a $100 million entry fee at the end of 2007 to be considered a serious candidate," Toner said in a recent interview.

The jockeying for the presidential nominations in both major parties is already vigorously underway, as illustrated by the parade of GOP contenders on display this weekend at a meeting of the Southern Republican Leadership Conference in Memphis. For now, however, the main arena of competition is financial, as candidates prepare themselves for a race most analysts believe will involve sums vastly larger than those spent on previous presidential campaigns.

Many political operatives are expecting that the gradual breakdown of the public funding system -- federal funds in exchange for spending limits -- that has taken place in recent years will become complete in 2008. The result would be candidates in both parties racing far past old spending records, and facing new pressure to begin raising money far in advance of the election year.

Not all political finance experts and campaign operatives agree with Toner that raising $100 million over the next 22 months is the price of admission for candidates who want to establish credibility and compete on an equal footing. The $100 million is nearly three times the previous threshold for being regarded in national political circles as a first-tier candidate. But it is plain that a number of factors have converged that will render obsolete old assumptions about what it costs to run for president.

First among those factors is the 2004 precedent. President Bush and Democratic nominee John F. Kerry decided then to do without public matching funds in the nominating phase of the campaign -- money that came with a requirement to limit spending to just $44.7 million each. They went on to raise $274.7 million and $253 million, respectively, before accepting public funding for the general election campaign in the fall. Their success established what many strategists believe will be a new norm in presidential politics.

What's more, many analysts believe that 2008 will be a clash of such titanic intensity that the nominees will reject public funding -- and the spending limits that govern it -- even for the fall campaign. If so, most bets are that each major-party candidate would need to raise in excess of $400 million by the Nov. 4, 2008, election. Candidates would want to raise as much of that money as early as possible, so as not to waste precious campaign time holding fundraisers.

Steve Elmendorf, the deputy manager for Kerry's general election campaign against Bush, predicted that accepting matching funds is a "thing of the past in the primary and the general." Public funding of presidential campaigns was started in 1976 in the wake of the Watergate scandal.

A final factor inflating the pressure to raise money early is Sen. Hillary Rodham Clinton (D-N.Y.). She has a proven ability to raise money on a national scale, and if she runs for president in 2008 she will raise the stakes for competitors in both parties.

Other Democratic contenders, such as Sen. Evan Bayh (Ind.) or former Virginia governor Mark R. Warner, would need to raise money aggressively to avoid being swamped by sums. Many Republicans, meanwhile, believe that their candidates must base their fundraising strategies on the assumption that Clinton will turn down public financing and set a new standard for fundraising and spending in the fall campaign.

One Republican 2008 operative, discussing campaign strategy on the condition of anonymity, said it would be "irresponsible" for a candidate to be thinking solely about spending needs for a primary election campaign without weighing "the consequences of what Hillary is bringing to the financial table and how quickly a potential nominee will have to turn his attention to dealing with her campaign."

The practical effect of the revved-up fundraising race means that candidates who do not enjoy national name recognition or a national fundraising network must troll the country relentlessly to build relationships with wealthy individuals in key donor states such as New York, California and Florida.

Take Bayh's schedule over a week last month. After appearing on a Sunday morning talk show on Feb. 19, Bayh flew to Fort Lauderdale for a reception and dinner hosted by Mitchell W. Berger, a lawyer and a leading fundraiser for Kerry and former vice president Al Gore.

The following day Bayh headed to Los Angeles, where he stayed for five days. He met with a Who's Who of West Coast money men, including DreamWorks co-founder David Geffen, Phoenix Pictures head Mike Medavoy, 20th Century Fox co-Chairman James W. Gianopulos and Artists Production Group executive Mark Canton. After spending the weekend in Washington, D.C., Bayh flew to New York on Sunday, Feb. 26. He met with prospective donors on Monday and returned to Washington late Monday night.

"It's the organizational prowess and ability to put together a national organization to raise money that is the real test, and it's that ability that translates into dough," said an adviser to a potential 2008 Republican candidate.

The standards of the "money primary" vary depending on a candidate's strategy. For a front-runner, $100 million by Dec. 31, 2007, may be the goal, but candidates trying merely to become the main challenger face a lower hurdle.

Ron Kaufman, who is helping Massachusetts Gov. Mitt Romney (R) explore a bid, said the competition to become the challenger would require much less because $40 million to $50 million is more than enough to compete in the early caucuses and primaries. A victory early on would spark a financial outpouring to sustain the remainder of the campaign.

Kaufman's view was shared by supporters of Sen. Clinton, who is expected to have little trouble raising $100 million by the end of 2007 if she runs. The Clinton backers said a legitimate challenger to her would need to raise between $35 million and $40 million to finance strong campaigns in Iowa, New Hampshire and other early states.

If the pattern of 2004 holds for 2008, the huge surge in small donations over the Internet and through direct mail will not begin until two candidates have effectively locked up their respective nominations, probably in early March 2008.

Before then, candidates will be much more dependent on raising large contributions of up to $4,000; a candidate preparing to reject the general election public subsidy can accept a maximum of $4,000 from an individual -- $2,000 for the primary and $2,000 for the general election campaign. (The money collected for the fall campaign must be kept in a separate account and returned to donors if the candidate fails to win the nomination.)

One of the least known but most important dimensions of the early competition to raise cash is securing the support of men and women who have proven effective in the past at raising large sums -- usually from a well-tended network of business associates, corporate subordinates and clients.

The 2004 Bush campaign designated these people as "Pioneers" (raised $100,000), "Rangers" ($200,000) and "Super Rangers" ($300,000).

Texas lawyer Thomas G. Loeffler, a Bush Ranger in 2004, has already signed on to help Sen. John McCain (R-Ariz.) in 2008; Northern Virginia real estate developer Dwight C. Schar, a Ranger in 2004, was on the host committee for a Super Bowl fundraiser to benefit Sen. George Allen (R-Va.). A senior GOP strategist said these Bush backers undoubtedly are "being swarmed over" by the president's would-be successors.

The 2008 fundraising marathon has its roots in the 2000 GOP nominating contest. Determined not to be outdone by publisher Steve Forbes's ability to self-finance a campaign, Bush opted out of the federal matching funds system for the Republican nomination. Instead, he raised $70 million in 1999 -- then a staggering new record -- and $101.5 million by the time he received the nomination. Since then, a GOP operative said, other front-runners have been tempted to intimidate rivals with a "shock and awe" approach to early fundraising.

Former Vermont governor Howard Dean caused a sensation on the Democratic side by raising $41 million by the end of 2003 for his presidential campaign, much of it in small donations from grass-roots activists. Though that was double what eventual nominee Kerry raised in 2003, that kind of money almost certainly will turn no heads in the next cycle.