Speier chose Leo J. Ryan Park in Foster City to announce her candidacy Sunday. The park is named in honor of the former congressman for whom she worked nearly 30 years ago.
Ryan was gunned down and Speier nearly killed in Guyana by the followers of the Rev. Jim Jones in 1978.
Speier will running to replace the 79-year-old Lantos, who announced two weeks ago that he would retire at the end of his term because he is battling cancer of the esophagus.
The Democratic primary race to succeed Lantos -- who has served 14 terms in the House -- could also include state Senator Leland Yee of San Francisco.