Updated 1:16 p.m.| The Congressional Leadership Fund, a super PAC backed by House Republican leadership, announced Thursday it had expanded to 27 offices nationwide.

In August, the super PAC announced it had 17 field offices in districts like Illinois’ 12th, Kansas’ 3rd, New Jersey’s 3rd and 7th, and Pennsylvania’s 6th and 7th districts.

The announcement on Thursday placed offices in a number of districts with vulnerable Republican incumbents.

• California’s 45th District, where Mimi Walters is facing seven Democratic challengers. Walters’ district is in the suburbs of Orange County and broke for Hillary Clinton.
• Illinois’ 6th District, where Rep. Peter Roskam is facing multiple Democratic challengers.
• Colorado’s 6th District, where Rep. Mike Coffman is a perpetual target for Democrats given his district voted for both Barack Obama and Hillary Clinton. Coffman voted for the tax bill but also voted against the Republican health care bill last year.
• Kentucky’s 6th District, where Rep. Andy Barr is facing retired Marine fighter pilot Amy McGrath and Lexington Mayor Jim Gray, who lost in his challenge against Sen. Rand Paul in 2016.
• Michigan’s 8th District, where Rep. Mike Bishop is facing two Democratic challengers, including Elissa Slotkin, a former Pentagon official in the Obama administration.
• Pennsylvania’s 16th District, where Rep. Lloyd K. Smucker is running in a race Inside Elections with Nathan L. Gonzales rates Leans Republican.
• Texas’ 7th District, where Rep. John Culberson is facing seven potential Democratic challengers after his district broke for Hillary Clinton last year.
• Texas’ 23rd District, possibly the most competitive district in the Lone Star State, where Rep. Will Hurd is seeking a third term. Hurd is facing multiple challengers in a district that broke for Clinton. He voted for the tax bill but against the Republican health care bill.
• Iowa’s 1st District, where Rep. Rod Blum won re-election in 2016 after Democrats mistakenly tried tying him to President Donald Trump.
• Virginia’s 2nd District, where Rep. Scott Taylor saw many counties in his district vote for Democrat Ralph Northam in last year’s gubernatorial race.
• Washington’s 5th District, which is represented by Rep. Cathy McMorris Rodgers, chairwoman of the House Republican Conference, despite the fact the district is rated Solid Republican by Inside Elections with Nathan L. Gonzales.

“CLF is taking nothing for granted as we focus on our mission to maintain the House Republican majority,” CLF Executive Director Corry Bliss said. “We have rejected the traditional model of super PACs and are doing things differently by operating a national, data-driven field program.”