California Republican Darrell Issa will not seek reelection, he announced Wednesday. Issa narrowly won reelection in 2016. His roughly 0.5% margin of victory over Democrat Doug Applegate was one of the five closest congressional races in 2016. Hillary Clinton won the district by 7.5%, one of only 23 districts nationwide (7 in California) that elected a Republican to the House while supporting Clinton over Trump in the presidential election.

Sabato's Crystal Ball has moved the 2018 race for the 49th district from Toss up to Leans Democrat.

Serving #CA49 has been the privilege of a lifetime. From the bottom of my heart - thank you - to everyone for your support and the honor of serving you all these years. My full statement on my decision not to seek reelection: https://t.co/zjlkeiqnzs

— Darrell Issa (@DarrellIssa) January 10, 2018

Issa is the 2nd California Republican to retire this week. Ed Royce announced his retirement on Monday.  That race moved from Leans Republican to Toss Up.

Worth Noting: Ratings for these races assume a Democrat vs. a Republican face off in November. However, California has a non-partisan primary, where all candidates compete on a single ballot, with the top two, regardless of party, moving on to November. Depending on the composition of the ballot it is possible for two candidates from the same party to advance to November, even in swing districts like Royce's 39th and Issa's 49th.

45 members of the House are retiring or seeking another office in 2018. Arizona Rep. Martha McSally will be added to this list Friday if, as expected, Rep. Martha McSally (R, AZ-2) announces her candidacy for U.S. Senate in Arizona. Ohio's Pat Tiberi (R, OH-12) will be removed from the list when he resigns on January 15th.