By Rachel Kapochunas, CQ Staff

California Democratic Rep. Tom Lantos ’ retirement announcement Wednesday put former Democratic state Sen. Jackie Speier at the top of his list of successors in the highly Democratic 12th District — at least for the time being.

Speier, a lawyer, established an exploratory campaign for the seat and has been the only candidate who has taken steps toward running in the district.

Speier had indicated she planned to challenge Lantos from the left in the June 3 Democratic primary but Lantos was highly favored to win re-election. Lantos, who turns 80 next month, has served in Congress since 1980 and has easily dominated his re-election contests since 1984. Lantos announced Jan. 2 that he had been diagnosed with esophageal cancer and would not seek re-election to his San Mateo-area seat.

Without Lantos on the Democratic primary ballot, Speier has a much stronger chance of winning the Democratic nomination, but an open seat race is bound to attract additional Democratic candidates who will be eager to run in the strongly left-leaning district. State Sen. Leland Yee already had been named as a potential candidate for the seat prior to Lantos’ announcement.

“In the coming days, we will take a hard look at the challenges this district faces in filling the shoes of Congressman Lantos, but today is not the day to be thinking about future political office,” Yee said in a statement noting that his “thoughts and prayers” were with the congressman and his family.

Speier also avoided talk of the impending election, releasing a statement regarding her concern for the congressman’s health. “Congressman Lantos has overcome many hurdles in his life and I hope and pray he’ll overcome this one,” Speier said.

CQ Politics rates the race as Safe Democrat.

Because the San Mateoa?`San Francisco area is such strongly Democratic turf, little attention is likely to be paid to the Republican field

Lantos won re-election in 2006 with 76 percent and has dominated his re-election contests since 1984. Democratic gubernatorial candidate Phil Angelides carried the district in 2006 with 50.5 percent of the vote despite losing statewide by 17 percentage points to Republican Gov. Arnold Schwarzenegger .

Speier has yet to establish an official campaign but news reports indicate she has hired staff to begin preparing her candidacy.

In addition to Speier’s state legislative service, she previously served as a congressional aide to Democratic Rep. Leo Ryan. Speier accompanied Ryan on a 1978 trip to investigate abuses at the Jonestown cult settlement in Guyana. A group including Ryan and Speier attempted to fly home on Nov. 18 when they were ambushed at the airstrip of Port Kaituma. The congressman was killed along with several other people in the shooting and Speier, then age 28, survived five gunshot wounds.

Speier ran to succeed Ryan, but lost. The seat went to Republican Bill Royer in the 1979 special election, but Royer’s congressional service was cut short by Lantos who ousted Royer in the 1980 election for a full term.

Speier ran for California lieutenant governor in 2006, but lost a bid for her party’s nomination by 3 percentage points in a three-way primary.

Lantos currently serves as Chairman of the Foreign Relations committee. He said he plans to undergo treatment while finishing out his current term ending in January 2009.

Lantos, a native of Hungary and the only Holocaust survivor ever elected to Congress, on Wednesday expressed his appreciation for America.

“It is only in the United States that a penniless survivor of the Holocaust and a fighter in the anti-Nazi underground could have received an education, raised a family, and had the privilege of serving the last three decades of his life as a member of Congress,” Lantos said. “I will never be able to express fully my profoundly felt gratitude to this great country.”

Edward Epstein contributed to this story.

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