LOS ANGELES -- A court-ordered election here Tuesday will enable Hispanics to elect their first Los Angeles County supervisor in more than a century and also could undo conservative control of the five-person board in the nation's most populous county.

While the board is nonpartisan, conservative Republicans have held firm control for a decade. Liberals, now outnumbered 3 to 2 on the board, often have complained that supervisors have been overly responsive to developers and insufficiently concerned about declining health services and environmental issues.

"Three to two, three to two, we always know just what they'll do," goes an old jingle of the public employees union.

But what the board does could change after Tuesday's election in the new 1st Supervisorial District that sprawls across east Los Angeles and 21 cities in neighboring San Gabriel Valley. The vast district was created to enable Hispanics to elect a supervisor after a federal court determined that boundaries of existing districts had been drawn deliberately to prevent election of an Hispanic.

Pete Schabarum (R), the conservative who represents the present 1st District, is retiring after an appeal by the board reached the Supreme Court but failed to undo the redistricting.

State Sen. Art Torres (D), 44, a veteran of 16 years in the state legislature, is widely perceived as leading in the race to replace him. He sponsored legislation that would have provided $24 million for county trauma centers and other health services rapidly being cut back. The bill was vetoed by then-Gov. George Deukmejian (R), Torres said, because the board's conservative majority did not support it.

The board's political balance would change even more with election of combative Los Angeles Council member Gloria Molina (D), 42, described by herself and her opponents as the most liberal candidate in a field of nine candidates, four of whom have waged major campaigns. She depicts herself as a foe of the political establishment, of which she says Torres is a member.

The political direction probably would change less if either of the other major candidates is elected. They are Sarah Flores, 52, the only Republican in the race, and state Sen. Charles Calderon (D), 40, of Whittier.

Flores worked for 18 years as an aide to Schabarum. Although a less polished speaker than the three other major candidates, she has campaigned doggedly and could be the beneficiary of an absentee-ballot campaign directed largely at Republican voters.

Calderon is a moderate who belonged to a group of five state legislators who challenged the leadership of liberal Democratic Assembly Speaker Willie Brown. He trails other candidates in fund-raising.

Torres has raised the most money, nearly $500,000, and is the only candidate who has used television commercials, on the local station that carries Cable News Network. He also has been endorsed by KNXT, the news radio station with the largest audience in southern California. Other candidates have relied almost entirely on mailers and personal appearances.

While Torres is the favorite, even his supporters acknowledge that a runoff election may be necessary. A runoff is planned Feb. 19 between the top two finishers if no one receives a majority.

"Turnout is the great mystery," said George Pla, a Los Angeles businessman and Democratic political activist supporting Torres. "It's difficult to gauge the turnout in an election that will be held the day after a holiday in a completely new district, and the war has provided a further diversion."

The irony of the election is that non-Hispanic voters are likely to determine the outcome. While Hispanics, most of them Mexican American, comprise 70 percent of the population in a district of 1.8 million people, they are little more than 50 percent of the registered voters and likely to be even less of the electorate.