The post-election day vote count in California continued to smile on Democratic House candidates Tuesday, as a Central Valley Republican went down to defeat and another GOP incumbent fell behind in Orange County.

Rep. Jeff Denham of Turlock (Stanislaus County) was defeated by Democratic challenger Josh Harder, a venture capitalist who was raised in Turlock and moved back to the 10th District in 2017. Harder forged ahead in the district last week, and on Tuesday was leading, 51.3 to 48.7 percent.

In Orange County, Democrat Katie Porter took the lead over GOP Rep. Mimi Walters of Irvine by 261 votes Tuesday after having trailed since election day.

Porter, a UC Irvine law professor, had 50.06 percent of the vote after 12,510 votes were counted Tuesday from Orange County. Walters is trying to win a third term in the 45th District.

The Denham and Walters seats were among seven held by the GOP that Democrats targeted in the midterm elections as winnable, given that Hillary Clinton carried them in the 2016 presidential election. Democrats have flipped three other House seats in Southern California.

Another Orange County contest remained too close to call: In the 39th District, Republican Young Kim was clinging to a 839-vote lead Tuesday against Democrat Gil Cisneros. The seat is now held by GOP Rep. Ed Royce of Fullerton, who is retiring.

In the seventh Democratic-targeted district, Republican Rep. David Valadao of Hanford (Kings County) extended his lead to 2,399 votes over Democratic businessman T.J. Cox. Valadao now has 51.4 percent of the vote.

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli