The group says it is only targeting safe districts where there is an entrenched incumbent and a credible challenger — although in some cases, including that of Manzullo, the challenger is a more junior member of the House. (The group also backed Rep. Dennis Kucinich (D-Ohio) in his redistricting-induced primary against Rep. Marcy Kaptur (D-Ohio), who had been in the House longer than Kucinich, but Kaptur still won the primary.)

"The full measure of the success of our efforts will be seen in the next election cycle when more primary challengers step forward, giving voters a choice and an opportunity to participate in competitive elections," said Curtis Ellis, the campaign's spokesman.

The Campaign for Primary Accountability also released a list of races on its "watch list" for the second quarter of 2012, signaling to those lawmakers that they can be targeted in the near future. 

In New York, the group is watching Reps. Nydia Velázquez (D), Charles Rangel (D) and Edolphus Towns (D). In North Carolina, Rep. Howard Coble (R) is in the group's sights.

Texas lawmakers facing scrutiny by the group include Republican Reps. Ralph HallRalph HallGOP fights off primary challengers in deep-red Texas Most diverse Congress in history poised to take power Lawmakers pay tribute to Rep. Ralph Hall MORE, Joe Barton, John Culberson, Kevin BradyKevin BradyBorder-adjustment tax proposal at death’s door Mnuchin asks Congress for clean debt hike before August Overnight Finance: Inside Trump's first budget | 66 programs on the chopping block | Hearing highlights border tax divide | Labor to implement investment adviser rule MORE, Mike Conaway, Lamar Smith and Kenny Marchant, and Democratic Reps. Rubén Hinojosa and Lloyd Doggett.

House members from California attracting the group's attention include Republican Reps. Dan Lungren, Gary Miller, John Campbell and Brian Bilbray, and Democratic Reps. Pete Stark, Jim Costa, Anna Eshoo, Adam SchiffAdam SchiffUncertainty builds in Washington over White House leaks Schiff: Kushner's security clearance should be reviewed Schiff: Anyone working for Trump 'at risk of being used' MORE, Grace Napolitano, Henry Waxman, Joe Baca, Karen BassKaren BassTechnology's role in human trafficking cannot be ignored Dem rips Trump's claim of historically unfair treatment Los Angeles School Board race takes center stage in battle for public education MORE, Lucille Roybal-Allard and Maxine Waters.

The campaign is also watching the New Jersey primary between Democratic Reps. Bill Pascrell and Steve Rothman, plus two redistricting-induced California primaries: Rep. Howard Berman (D) versus Rep. Brad Sherman (D) and Rep. Janice Hahn (D) versus Rep. Laura Richardson (D).