Washington (CNN) Democrat TJ Cox on Monday night pulled ahead of Republican Rep. David Valadao in the race to represent California's 21st Congressional District.

According to the California Secretary of State's Office, Cox now leads by fewer than 500 votes. According to the website, Cox has received 55,672 votes to Valadao's 55,236 votes.

CNN had previously projected the race for Valadao, as had other national news outlets. Vote reports after Election Night tightened the margin significantly, and the latest update from Kern County put Cox in the lead by just over 400 votes. CNN has now withdrawn its projection in the race.

Democrats have picked up a net gain of 38 seats, and will hold 233 seats in the House of Representatives, according to CNN's projections. Two races remain uncalled -- CA-21 and New Mexico's 2nd Congressional District. The Democratic candidate leads in both races. Democrat Xochitl Torres Small is ahead of Republican Yvette Herrell in NM-2. Both districts are Republican-held seats.

Republicans will hold 200 seats in the House, according to CNN's projections.

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