SAN DIEGO — Two prominent San Diego Democrats, once allies on a variety of issues, are trading leads in the early results for a pair of California State Assembly races.

The split contests are due to California re-districting.

David Alvarez and Georgette Gómez are competing in a run-off to finish a former lawmaker’s term in the old 80th Assembly District. At the same time, they’re also vying to represent the new 80th district for a full term.

Because the old and new districts have so much overlap, many voters made a selection in both races. But others only voted on one or the other, and that difference appeared to be driving a split in the initial batch of results released shortly after polls closed.

A map shows the overlap, and differences, between the old and new 80th Assembly District. Some voters have two elections for the seat on their ballot for this reason. (Photo: County of San Diego)

On the ballots already counted late Tuesday, Alvarez led the special election run-off to fill the vacancy left by Asm. Lorena Gonzalez, who vacated the seat to take a position in California labor leadership.

Alvarez had about 54% of the vote — almost a 10% lead over Gómez, with many ballots left to be counted. If that leads hold, he’ll get to finish out Gonzalez’s term until the end of the year.

But it’s Gómez who fared better in the early results for a full term in the newly drawn 80th district. In that race, she held a slim margin over Alvarez, about 36% to 30% in the early returns.

The results indicate that Gómez and Alvarez will move on to yet another contest — a run-off in the November general election for that full-term seat in the new district. And if the early numbers hold, it appears Gómez could have a better shot at victory under the newly drawn boundaries than the old.

The old and new 80th districts encompass large portions of the South Bay and southern San Diego, including Barrio Logan where both Alvarez and Gómez grew up. The two have campaigned together and advocated for similar causes during political careers as Southern California Democrats. Both served on San Diego City Council.

During the recent campaign, however, the two have staked out different claims in their solid blue districts.

Alvarez has courted support from local business leaders, along with elected Democrats including Mayor Alejandra Sotelo-Solis of National City. Gómez has emphasized her endorsements from the party’s progressive wing, along with elected officials including Mayor Todd Gloria and County Supervisor Nathan Fletcher.

The sparring of multiple campaigns has ended what was once a personal friendship between the two, Gómez recently told Voice of San Diego.

It all sets up for yet another bruising matchup in November.