California is Reagan country, but the state's Democrats have a big stake in Walter Mondale's bringing his presidential campaign here. Mr. Mondale and vice-presidential nominee Geraldine Ferraro will make fund-raising appearances in California, and party officials hope that instead using that money to campaign elsewhere the candidates will spend it here.
A strong Democratic turnout in November is especially important, state party leaders say, not so much to maintain control of the legislature or even for the presidential race, but to defeat a pack of Republican-inspired ballot initiatives that strike at the heart of the Democratic Party and constituency.
State Democrats expect to spend more than $4 million on campaigns countering initiatives that deal with campaign spending, reapportionment of congressional districts, welfare spending, and an effort to keep municipalities from raising taxes to compensate for Proposition 13 losses.
That effort could produce a reverse coattail effect benefiting Mondale; and Mickey Kantor, California campaign chairman for the former vice-president, says he views the anti-initiative drive as a plus for the presidential ticket.
''We're not writing California off,'' Mr. Kantor insists. But specific state campaign plans have not been made, he explains.
''I'm convinced they're making California a priority state,'' said US Sen. Alan Cranston, following a July 25 conversation with Robert Beckel, Mondale's national campaign chairman.
Michael Roos, majority floor leader in the state Assembly, concurs, suggesting that priorities will be clear only when the campaign begins in earnest - say, in October. But he adds, ''Clearly, since 1980 or even '76, the upper ticket hasn't been dragging the lower part, it's been the lower pulling the upper on its coattails. If Mondale runs close (in California), it'll be because we've dragged him.''
California Democrats want the presidential ticket to carry its weight in the state, and they think it can, largely because of the excitement Geraldine Ferraro has added. The thought that Mondale and Ferraro might come into the state to raise money and then use most of it elsewhere discomfits them.
California has not gone Democratic in a presidential election since Lyndon Johnson carried the state against Barry Goldwater in 1964, and that factor has discouraged Democratic candidates from spending much time or money on the state. In 1980, President Carter conceded to Ronald Reagan before the polls closed here - an incident that heightens the feeling by California Democrats that the state could be written off by Mondale strategists.
They are looking for an early commitment from Mondale that he will campaign seriously on Reagan's home turf. State Democratic chairman Peter Kelly says he has been negotiating with the Mondale campaign to plow a ''six-figure'' sum of money back into California from funds raised here.
US Rep. Tony Coelho of California, who chairs the Democrat's Congressional Campaign Committee, says the six figure sum would be ''a kind of down payment,'' because ''California is a state that's going to raise a lot of money, and they can't say 'we want to export your money but not do anything for your state.' ''
''I worry about any taking of the natural resources out of California that ought to be used in California by the national ticket,'' says Willie Brown, speaker of the state Assembly. Democrats here want the money put back into voter registration drives, direct mailings, and get-out-the vote projects.
''Democrats (in California) have to run a campaign with or without Mondale because there are three or four propositions (on the ballot) injurious to the party. We'll get help from the Mondale people - how much help I don't know,'' says state Treasurer Jesse Unruh, one of the California's most powerful Democrats.
One political reality, he points out, is that ''if there's a better chance of carrying enough other states,'' it would be logical to focus campaign energy there instead of California, even though it does have the largest block of electoral votes, 47.
Representative Coelho says if there weren't a chance for Mondale to win, Californians wouldn't expect him to expend resources here. But Democrats here tick off a number of reasons why they think Mondale could win in Reagan's home state - chief among them the excitement Ferraro has generated here.
Former state party chairman Bert Coffey says the Ferraro element ''has changed the whole picture in California.''
Other factors favorable to the Democratic ticket in California here include:
* The ''California tone'' set by the successful convention and the consideration of Californians Dianne Feinstein and Tom Bradley as vice-presidential material.
* The enormous volunteer network left over from the convention and ready to be employed in the campaign.
* Special-interest group support on issues like the nuclear freeze and environmentalism - issues on which Reagan is considered vulnerable.
* A large minority population - chiefly Hispanics - that is expected to vote Democratic but needs to be tapped through registration drives.