Proposed Senate Districts Protect Most Incumbents : Remapping: Democrats would keep power. Latinos and Republicans could post some gains.

Unveiling a plan that could shape representation in the state Senate into the next century, Democratic and Republican leaders proposed new districts on Wednesday that they said probably would result in the election of more Latinos and Republicans while leaving Democrats in charge of the Legislature’s upper house.

With a few notable exceptions, the proposed boundaries, based on the 1990 U.S. Census, appear to leave incumbents comfortably in command of the districts they hold today.

The proposal would add one new Latino-controlled district in Los Angeles County and substantially boost Latino clout in two other districts, one based in San Diego and the other in the San Joaquin Valley.

Blacks would retain voting power in the two Los Angeles districts now represented by blacks. Asians would remain concentrated in existing districts, but would not be numerous enough to control any seat.

The plan also would add a Republican-leaning district to the fast-growing Inland Empire at the expense of Los Angeles County, which would lose a district held by a Democrat. One San Joaquin Valley seat in the hands of Democrats would be tilted to favor Republicans.

Although many cities and counties would be split by district lines, Senate leaders said the proposed boundaries were dictated in large part by the federal Voting Rights Act, which requires the Legislature to maximize the political power of minority communities.

“Cities were purposely split and strange boundaries created because of the importance of the Voting Rights Act,” said Democratic Senate Leader David A. Roberti of Los Angeles, who added, “We have strengthened existing minority districts and added new ones.”

A spokesman for the Mexican American Legal Defense and Educational Fund, which has been lobbying for greater Latino representation, said after a quick review of the proposed districts that the plan appears to conform with suggestions made by the group.

“They’re in the ballpark, and not necessarily out in left field, either,” said Arturo Vargas, director of policy for MALDEF, which will release its own proposed lines today. “Those appear to be the general concepts we have been promoting.”

The proposed district boundaries will be put into legislation and voted on by the Senate and Assembly, both of which must approve the boundaries for them to become law. The plan also needs the signature of the governor or a two-thirds vote in each house to override a veto. Gov. Pete Wilson did not comment on the proposal Wednesday.

Boundary plans for the Assembly, Congress and the State Board of Equalization are being drafted separately and are expected to be released next week.

Roberti and Senate Republican Leader Ken Maddy of Fresno said the proposal will almost certainly be changed before it is enacted.

“This is not the end,” Roberti said. “These plans should be regarded not as some sort of final, non-negotiable offer but rather as a good effort, which we want help in finishing.”

But with only a little more than a week remaining before the Legislature’s scheduled Sept. 13 adjournment, senators and aides indicated that the changes probably will be limited to minor tinkering along district borders and not wholesale shifts of boundaries.

Throughout their joint news conference, Roberti and Maddy focused on the Voting Rights Act and the fact that a handful of incumbents were finding their districts radically changed or, in one case, moved to another county.

The most dramatic impact on an incumbent would be in the proposed 33rd District. That district, represented by Democrat Cecil Green, straddles the Los Angeles County and Orange County line. In the new plan, the district would be collapsed and moved east to straddle the border between Riverside and San Diego counties, where it would be dominated by Republican voters.

Sen. Ralph C. Dills of Gardena, also a Democrat, would see the 30th District he represents changed into a predominantly Latino district meandering from northern Long Beach to Alhambra in the San Gabriel Valley. The Democratic-dominated district’s population would be 68% Latino and its voter registration 41% Latino.

Other Latino gains would come in the 40th District, represented by Democrat Wadie P. Deddeh, which would retain its southern San Diego County base but loop east to include Imperial County and part of Riverside County, increasing its Latino population from 36% to 48%. The boundaries of the 12th District in Central California, represented by Democrat Dan McCorquodale, would be moved south, farther into the San Joaquin Valley, to increase its Latino population from 20% to 43%.

Also in the San Joaquin Valley, the 15th District represented by Democratic Sen. Rose Ann Vuich of Dinuba, would lose its Fresno County base and move as far south as the Mojave Desert. The voter registration would change from a nine-point edge for Democrats to a three-point advantage for Republicans.

But a review of the numbers supplied with the proposal shows that most incumbents would find their futures just as secure under the new boundaries as those currently in use.

Of the 40 Senate districts, for example, 23 would see an increase in the voter registration of the party that now holds the seats. Although the other 17 would nominally become more competitive than they are today, most would still remain solidly Democratic or Republican. At least 12 of those districts would continue to have a registration edge of more than 15% for one party or the other.

Looked at another way, the average district’s voter registration favors one party or the other by 21.2%. Under the new plan, the average gulf between the parties would drop to 20.9%.

“It’s an incumbent protection plan, with a few exceptions,” said Sen. Lucy Killea of San Diego, a Democrat who recently said she will become an independent.

Roberti acknowledged that he does not expect the plan to have a major impact on the partisan makeup of the house, which Democrats have controlled for two decades, even as the party’s statewide registration edge over Republicans has narrowed.

Democrats account for 49.49% of the state’s voters; 39.26% are Republicans. Democrats control 26 Senate seats, with the Republicans holding 13. There is one independent.

Times staff writer Ralph Frammolino contributed to this article.

PROPOSED DISTRICTS: Brief descriptions of the proposed new state Senate districts that would fall within Los Angeles County. B2

At a Glance:

The Redrawn State Senate District 30

To maximize the voting power of minority groups, the state Senate is proposing to redraw the boundaries of the 30th District to bring in additional Latino voters.

The redrawn district, now represented by 81-year-old Ralph Dills, a Gardena Democrat, would retain only Paramount and Lynwood, losing Gardena, Carson and portions of Long Beach, San Pedro and Wilmington.

Alhambra, Cudahy, South Gate, Huntington Park, Maywood, Bell, Bell Gardens, Monterey Park, Commerce and Montebello all would become part of the new district. Population: 747,135 Registered Voters: 179,343 Latino Registration: 41% Party Registration:

Democratic: 66.42% Republican: 23.72%