The next US House seat that is a vulnerable Republican seat is California's 39th District.
It is held by Republican Ed Royce.
Royce is a Republican Party ticket voting man. Whatever they say, he votes and has voted for Trump positions 92% of the time. He is A rated by the NRA, and blamed Islamic Terrorists in a domestic domestic mass shooting in Florida. According to On The Issues voting record, he voted against marriage and adoption freedom and for government funded religious endorsement. He voted against freedom of speech, when the flag is involved. He supports a Muslim specific travel ban (discrimination). He voted to repeal poor people's healthcare and says Trump does not need to provide tax returns.
Royce declared a few weeks ago that he will not run for re-election. However, as he is a straight party voting man, this is what we can expect from the next GOP Trump Clone.
Royce sits in a Democrat state, and his district was Democrat for 10 years, prior to his election in 2013. The leading Democrat options at present are Andy Thorburn, Gil Cisneros, and Mai Tran.