He added that he would not pursue a "costly and time-consuming" recount.
The first-term lawmaker, whose accomplishments included crafting this year's extension of the film tax credit, was widely considered an ascendant leader in the Democratic caucus. He beat Lopez by nearly 40 points in the primary.
Lopez, in an interview last week, said she was inspired to run for office because she didn't believe "that people in Sacramento are paying attention to our needs."
An education advocate, she ran a bare-bones campaign; her supporters pointed to her grassroots network from her years of volunteer work as the force behind her surprise victory.
Analysts say a number of other reasons could explain the unexpected outcome, including extremely low turnout in the district. Ballot design may also have played a role.
Paul Mitchell, vice president of the bipartisan firm Political Data Inc., noted that in the other races listed on the ballot above the 39th Assembly District race, the Democratic candidate appeared before the Republican.
Lopez's ballot designation — "educational community representative" — may also have been more appealing than Bocanegra's designation as "Assemblymember," particularly with voters who had low approval of incumbents. In all, the confluence of factors was a "perfect storm" said GOP consultant Mike Madrid.