Washington (CNN) Democrat Xochitl Torres Small has defeated Republican Yvette Herrell in one of the nation's last outstanding House races, New Mexico's secretary of state certified Tuesday morning.

The official result brings the total number of Democratic gains in the House to 39 seats, with one race outstanding, according to CNN's count.

Herrell claimed victory in New Mexico's 2nd Congressional District race on election night earlier this month, but as ballots continued to be counted, Torres Small took a lead in the vote count in the race to replace outgoing GOP Rep. Steve Pearce.

As of midday Tuesday, CNN had yet to project a result in California's 21's Congressional District, where Democrat TJ Cox pulled ahead of Republican Rep. David Valadao on Monday evening.

Torres Small's win would swing a GOP-held seat for Democrats, bringing the party control over all three New Mexico US House seats once Pearce's current term ends.

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