San Francisco — Los Angeles Mayor Tom Bradley unofficially ended California's cliff-hanging gubernatorial contest last Saturday when he conceded - three days after the votes were totaled - that state Attorney General George Deukmejian had, indeed, eked out a narrow victory in the Nov. 2 election.
But while forgoing a recount, the defeated Democrat could not put an end to the speculation over what caused his loss when most voter polls projected a fairly easy victory. Even so-called ''exit polls'' - questioning of voters after they had cast their ballots - indicated Bradley was on his way to becoming the country's first elected black governor.
Political experts note that when an election is decided by seven-tenths of 1 percent of the electorate (3,775,819 for Deukmejian and 3,722,704 for Bradley), it is impossible to attribute defeat to any one cause. But two are being avidly discussed across California - racial bias against the Democratic candidate and the large turnout of conservatives in rural counties to defeat proposals for gun registration, beverage container deposits, and a water resources plan, and to vote against the nuclear freeze initiative (which won, but narrowly).
Mayor Bradley, in a campaign that carefully packaged him as the epitome of a moderate, mentioned the racial issue only once, saying that he did not consider it a significant factor. And so concerned was Mr. Deukmejian about a racial ''backfire'' that when William Roberts, his campaign manager, conceded that some people would vote against Bradley because he is black, Mr. Roberts was fired.
After his apparent defeat, Bradley stated: ''I said I did not believe race would be a significant factor. I never said it would be no factor.''
In an election-day sampling of voters by Mervin Field's California Poll, 4 percent of those polled indicated they supported Deukmejian because they did not wish to vote for a black.
More obviously significant in the defeat of the two top Democratic candidates in the Nov. 2 California election - Bradley for governor and outgoing Gov. Edmund G. (Jerry) Brown Jr. for US senator - was the huge turnout of rural, largely conservative, voters. While the vote was just under 70 percent statewide (almost 10 percent above the national average), more than 70 percent voted in most rural counties, and in some the turnout was 80 percent. Those counties went overwhelmingly for the two Republicans, while piling up huge majorities against gun control, the bottle bill, and a water plan designed to complete last June's victory over the proposed peripheral canal (to speed more northern California water to Central Valley farms and densely populated southern California).
California's political ''hot-stove league'' can also spend a good part of this winter speculating on why the Democrats fared so much better in contests for lower-level offices. Not only did the party win every statewide office but governor and senator, its state Assembly majority slipped by only one seat, to 47 to 33, and the Democrats' state Senate majority went up by five, to 25 to 15.
What's more, in the face of blistering criticism of the congressional redistricting plan masterminded by veteran Democratic US Rep. Phillip Burton of San Francisco, the party increased its California delegation in the US House of Representatives by seven - the two seats added as the result of the 1980 US Census and five others snatched from Republicans through redistricting.
Congressman Burton, a particular target of both state and national Republican organizations (and fundraisers) because of his ''gerrymandering'' role, defeated GOP state Sen. Milton Marks by 58 to 40 percent.
Voters in the June 8 primary had rejected the Burton congressional redistricting plan by a wide margin. Although it was too late to keep it from being used in the Nov. 2 election, a new plan has been ordered by the California Supreme Court before the 1984 elections. A Nov. 2 ballot meassure taking the redistricting power away from the Legislature and establishing a ''Districting Commission'' to do the job had been expected to pass. It lost, 45 to 55 percent.