Voters in San Diego County will cast ballots Tuesday to fill two state legislative seats being left vacant because of term limits.

Democrat Marty Block, president of the San Diego Community College District, will square off against Republican John McCann, a member of the Chula Vista City Council, in the 78th Assembly District.

Assemblywoman Shirley Horton, R-Chula Vista, cannot seek reelection because she is termed out of office.

The 78th Assembly District stretches from San Diego to Chula Vista and includes the cities of Spring Valley, Lemon Grove and parts of Bonita.

In the 75th Assembly District, Republican Nathan Fletcher, a businessman, will face Democrat Darren Kasai, a small business owner.

The 75th District, now held by termed-out Assemblyman George Plescia, R-La Jolla, includes the communities of Escondido, Poway, San Diego, La Jolla, Mira Mesa, Scripps Ranch, Rancho Santa Fe and Rancho Bernardo.

The remaining state legislative seats before voters appear safe for the incumbents.

In the 74th Assembly District, incumbent Assemblyman Garrick Martin, R-Solana Beach, will face Democrat Brett Deforest Maxfield, an attorney. The district includes Carlsbad, Del Mar, Encinitas, Escondido, Oceanside, San Marcos, Vista and parts of San Diego.

Assemblywoman Lori Saldana, D-San Diego, is the incumbent in the 76th Assembly District, which includes much of the central and northern portions of the city of San Diego. She will square off against Republican Ralph Denney, a business manager.

The 77th Assembly District seat is held by Assemblyman Joel Anderson, R-El Cajon. He will square off against Democrat Raymond Lutz, an engineer. The district includes El Cajon, La Mesa, Santee, Jamul, Lakeside, Ramona, Borrego Springs and parts of San Diego.

Assemblywoman Mary Salas, D-Chula Vista, will face Republican Derrick Roach, a fraud investigator, in the 79th Assembly District. The district includes Imperial Beach, Chula Vista, Coronado, National City, Otay Mesa and San Ysidro.

Sen. Christine Kehoe, D-San Diego, will face Republican Jeff Perwin, a small business owner, in the 39th Senate District, which stretches from Del Mar to downtown San Diego and east to Spring Valley.