SAN FRANCISCO -- Californians are nonchalant about the news of the Census Bureau's official confirmation this week of their status as the most populous and politically potent state in U.S. history. They see it for what it is: one more instance of Washington catching up to the facts.

The 29.8 million people, the 52-member House delegation and the 54 electoral votes -- one-fifth of those needed to elect a president -- all give California more clout than any state has had since the beginning of the Republic. And that power can only continue to grow. California passed New York in population to become No. 1 in the Census of 1970. With the relative growth rates of the past decade, it will be double New York in population in another 10 years.

All this underlines one of the strikingly neglected facts of post-World War II politics: While California has provided candidates for the Republicans' national ticket in seven of the past 10 presidential races (on the winning side all but once), California Democrats have not furnished their party a single plausible national candidate in all that time.

That partisan imbalance -- the Democrats' California talent drought -- explains as much about the Republicans' postwar dominance of the White House as the withering of the New Deal coalition, the shift of the South's electoral votes from the Democrats to the GOP or any other factor one can mention.

What makes it all the more remarkable is that the Democrats have been competitive in California politics for a long time. It is 32 years now since Edmund G. (Pat) Brown Sr. won the governorship for the Democrats, and in that span there have been only two years when Democrats did not occupy top statewide office -- the governorship or at least one of the two Senate seats.

But the only Democrats to seek the party's presidential nomination -- Edmund G. (Jerry) Brown Jr., as governor in 1976 and 1980 and Sen. Alan Cranston in 1984 -- failed ignominiously, running so badly they damaged themselves at home.

I have a hunch that this pattern is about to change. On Jan. 7, Pat Brown, 85, will administer the oath of office to his daughter, Kathleen, 45, as the newly elected treasurer of California. California will finally have a statewide Democratic official with the potential to be on the national ticket.

Kathleen Brown is at least two steps short of that status now -- but she has more going for her than any other Democrat in office here. After being elected twice to the Los Angeles school board in the 1970s, she took her experience as a public-finance attorney into the 1990 treasurer's race and beat an able, appointed Republican incumbent, Tom Hayes. She was the only challenger in either party to oust a statewide incumbent.

She said at the outset of the race that her greatest advantages were also her greatest liabilities -- "I am a woman, a Democrat and a Brown." But combining her mother's good looks, her father's charm and political smarts and her brother's skill as a media campaigner, she proved herself a formidable politician.

The office she won provides a fine, risk-free place for her to burnish her credentials while waiting for the next step. Most of Brown's contemporaries among California Democrats are eyeing the two Senate races that will be on the ballot in 1992 (with Cranston retiring and newly elected Republican Gov. Pete Wilson's appointee to his Senate seat also facing the voters).

While they are competing against each other for funds and votes, Kathleen Brown will be in the happy position of managing California's huge state bond business while kibitzing and on occasion criticizing Wilson's performance as governor. She can decide in her own good time whether to challenge him in 1994 or wait another four years, when she would be only 53.

Almost everyone who knows her expects her eventually to seek the governorship her father and her brother occupied for 16 years; the only question is when. If she succeeds in becoming the first woman governor of California and the first Democrat to win since 1978, she would have an obvious attraction to the national party.

Already, Brown talks in national terms. When I asked her about the term-limits initiative California voters passed in November over vigorous opposition of leaders of the Democratic legislature she replied: "I didn't support the initiative, but I sure identified with the voters' frustration with politics in Sacramento."

And then she added, deftly changing the subject: "I don't think supporting term limits helped Pete Wilson win, and I don't think it will help president Bush -- any more than all that 'soak-the-rich' rhetoric you heard in October will help the Democrats. The real issue is competitiveness -- how we hold our place in the world. Democrats should be talking about fairness, accountability and competitiveness. We need to be investing in our future. That's my focus for the next four years -- managing California's investments."

Those investments, I suspect, may pay remarkable political returns for Kathleen Brown and, just maybe, give the national Democratic Party belated reason to rejoice at California's growing ascendancy.