Maryland's eight members of Congress are expected to ward off lesser-known challengers following a sleepy primary season for the candidates in the heavily Democratic state.
Seven of the state's representatives are Democrats, and none of their seats is considered likely to change hands in Tuesday's primary. The state's two Senate seats are also held by Democrats, but neither is up for election this year. Democrats outnumber Republicans 2-to-1 in Maryland.
Republicans are only targeting one incumbent in November's general election, Rep. John Delaney of the 6th District. Delaney easily defeated longtime Republican Rep. Roscoe Bartlett in 2012 after the western Maryland district was redrawn to include portions of heavily Democratic Montgomery County in the Washington suburbs.
Delaney faces a likely general-election challenge from Republican Dan Bongino, a former Secret Service agent who ran unsuccessfully against Democratic Sen. Ben Cardin in 2012. In the GOP primary, Bongino is running against little-known Harold Painter Jr.
Joe Cluster, executive director of the Maryland Republican Party, said the party is putting all of its energy into Bongino's bid.
"The only race that will be competitive for us where we challenge somebody is Delaney's seat. Just because of numbers alone we have a shot at it, and we have a very solid candidate in Dan Bongino," Cluster said.
In the other seven districts, he said, "The way that the lines are drawn, they're just so gerrymandered that we have no shot at winning."
Bob Fenity, executive director of the Maryland Democratic Party, said Delaney's seat should be safe as long as he runs a strong campaign and communicates his record.
The state's six other Democrats have all won re-election easily in the past, and their primary challengers have little funding or name recognition.
House Democratic Whip Steny Hoyer is unopposed in the primary for the 5th District, which includes southern Maryland. Hoyer, 75, has represented the district since 1981. Three Republicans are seeking to mount a longshot challenge against him in November.
Rep. Elijah Cummings, the ranking Democrat on the House Oversight and Government Reform Committee, is seeking a 10th term representing the Baltimore-area 7th District against two little-known challengers. Two Republicans are also on the primary ballot.
After considering a run for governor, Rep. Dutch Ruppersberger, the top Democrat on the Intelligence Committee, is running for a seventh term against two challengers. Only one candidate is running in 2nd District for the GOP.
Rep. Chris Van Hollen, running for his eighth term in the 8th District, faces two Democrats in the primary. Only one Republican is running in the general election in the suburban Washington district.
Rep. John Sarbanes is seeking a fifth term representing the sprawling 3rd District in central Maryland. Three Republicans and one Democrat are also running.
In the 4th District, also in the Washington suburbs, Rep. Donna Edwards is seeking a third full term. She has one primary opponent, and four Republicans are seeking to run against her in the general election.
In the 1st District, Republican Rep. Andy Harris, a tea party stalwart, is seeking a third term and faces a primary challenge from Jonathan Goff Jr. of Harford County, a political novice. Democrats in the district, largely on the Eastern Shore, will choose between physician John LaFerla of Kent County and Bill Tilghman, an attorney and businessman from Queen Anne's County.
LaFerla was endorsed by Wayne Gilchrest, a moderate Republican whom Harris defeated in a 2008 primary.