For the first time in his politically successful career, Calif. Gov. Edmund G. (Jerry) Brown Jr. is finding it difficult to raise money or enthusiasm for a campaign.

Nearly two months after formation of the President Brown Committee, less than $400,000 has been collected to fund the Californian's quest for the 1980 Democratic nomination. This is about one-fourth of what a California fund-raising committee took in during a similar period when Brown was running for reelection in 1978.

"Money is difficult," acknowledges Brown campaign chairman Tom Quinn. "I expect it to be difficult until after the first few primaries."

Whether Brown will be around after those first few primaries is anyone's guess. Quinn considers Brown's effort to defeat both President Carter and prospective candidate Sen. Edward M. Kennedy "a longshot campaign, but not a frivolous one." This would appear to be a fair summary of the campaign mood, from Brown on down.

"I have nothing to lose," Brown told a reporter on the plane returning from his first campaign trip to New Hampshire. "Carter has a presidency. Kennedy has a legend."

It is Kennedy's near-candidacy that has been especially damaging to Brown, who is accustomed to being the focus of attention wherever he goes.

Speaking of the Kennedy phenomenon, Brown's executive secretary Gary Davis says: "It's like a tidal wave. It dominates everything in its path. The Kennedy influence is pervasive. There's no region of the country of industry that's immune. He's a senior partner in the Democratic Party, and he's developed inroads in everything."

The Kennedys for a long time have been influential in California where Edward, as a 30-year-old lawyer, campaigned for his brother John in 1960 and developed a following before becoming a national figure himself.

The latest survey by California pollster Mervin Field, taken in August, shows the Massachusetts senator a runaway winner in a three-way race with 59 percent of the vote compared to 17 percent for Brown and 16 percent for Carter.

Kennedy also is a big winner in a two-way race with either Brown or Carter. Brown's only consolation is that he runs ahead of Carter, 48 percent to 40 in a matchup with the president.

The Kennedy boom has undercut Brown in Hollywood, a key source of funds to him in his gubernatorial races. Brown reportedly has been working to keep his fund-raising sources alive in the entertainment industry but with limited success.

Thom Mount, a vice president of film and music conglomerate MCA/Universal, has organized a Kennedy fund raising group in the entertainment industry that started with 20 people in August and now numbers 300, including some former Brown supporters.

"If it was Jerry Brown against Carter, it would be easy for the entertainment industry to support Brown," Mount says. "But against Kennedy it's a totally different thing. Kennedy is seen as more desirable."

Still, Quinn and Brown fund-raiser Richard Silberman expect to raise enough money to compete vigorously in the New Hampshire primary Feb. 26 and the Massachusetts primary the week after that.

Federal expenditure limits are $250,000 for New Hampshire, and $900,000 for Massachusetts. Silberman estimates that Brown will spend close to the limits, perhaps $1 million combined for the two states.

If so, it would mean that half of the Brown campaign's end-of-the-year goal of $2 million would be consumed in these two primaries. Fund-raising after that is likely to depend on Brown's initial showings.

Brown hopes to finish ahead of Carter in either New Hampshire or Massachusetts and ahead of Kennedy in at least one of three subsequent Southern primaries -- Georgia, Alabama and Florida.

By the Illinois primary on March 18, in Quinn's view, Brown will have emerged as "the other candidate," the alternative to Kennedy.

The Brown fund-raising efforts have been limited by factors other than Kennedy, says Silberman. He observes that, traditionally, Brown has collected 80 percent of his contributions in sums of $5,000 or more, including corporate contributions that are legal under California law.

Federal campaign law, with its ban on direct corporate contributions and its $1,000 limit on individual givers, has proved a burden to Brown, who in the past has relied on the concentrated sources of Democratic wealth available in California and on the easy availability of such "extra" contributions as free offices and free car rentals. In a presidential race these are counted as in-kind contributions and charged against the $1,000 limit.

And despite Carter's political slump, says Silberman, a number of Democratic contributions are reluctant to come out against the president. While Silberman believes that many of these people ultimately will contribute to Brown or Kennedy, "they don't feel a compulsion to do anything in a hurry."

Most of the money Brown is attracting comes from California businessmen who are pleased with his fiscal conservatism, especially his conviction that the federal budget must be balanced.