For the second straight week, voters in four states will choose major party nominees for races with big stakes in November's midterm elections.
Pennsylvania, Nebraska, Idaho and Oregon hold primary elections Tuesday for races for the House, Senate and governor. The busiest slate will take place in swing state Pennsylvania, where a new congressional map has made Democrats more competitive in several House districts.
Democrats and Republicans will pick candidates for a handful of House races crucial to November's battle for the chamber. If Pennsylvania swings the Democrats' way, the party can pick up a good chunk of the 23 seats it needs to win to take control of the House in November.
Here are the races to watch on Tuesday:
Earlier this year, the Pennsylvania Supreme Court struck down a congressional map drawn by Republicans. Over GOP objections, the court redrew districts.
The changes made the state more hospitable for Democrats. Nonpartisan election analysis site Cook Political Report rates seven GOP-held seats as competitive or favoring Democrats. Another nonpartisan site, Sabato's Crystal Ball, lists six Republican-held districts in those categories.
Republican departures have helped the minority party. In three important races in the state, a GOP incumbent has either resigned or announced his intention to retire.
Several House districts in Pennsylvania will feature competitive races either on Tuesday, in November or both.
Others to watch: The primary elections in Pennsylvania's 6th and 17th Districts may not carry much drama. But the races for those seats in November will be critical. GOP Rep. Ryan Costello declined to run for re-election in the 6th District, now a "D+2" seat, according to Cook. Chrissy Houlahan, a businesswoman who served in the Air Force Reserve, runs unopposed on the Democratic side. Attorney Greg McCauley faces no opponents in the Republican primary. Houlahan would enter the general election as a favorite.
The 17th District features a rarity in congressional elections: two incumbents. Democratic Rep. Conor Lamb won a March special election for the state's previous 18th District but lives in the revised 17th District. Both he and GOP Rep. Keith Rothfus will run unopposed in Tuesday's primaries. Cook rates it as an "R+3" seat — less red than the area Lamb won in March.
Two Democrats vie Tuesday for the nomination in Nebraska's 2nd District. The winner will face unopposed GOP Rep. Don Bacon in a race nonpartisan handicappers consider a toss-up.
Moderate former Rep. Brad Ashford, who lost to Bacon by 1 percentage point in 2016, aims to win back his seat. He faces nonprofit executive Kara Eastman, who is running to his left.
GOP Rep. Lou Barletta, an early Trump supporter who endorsed the president in March 2016, aims to win Pennsylvania's Republican Senate primary on Tuesday. The congressman, who has pushed to crack down on immigration since serving as mayor of Hazleton more than a decade ago, has tried to channel Trump to capture the president's success in the swing state.
Trump aimed to give Barletta a late boost, recording a robocall that went out to Pennsylvania voters on Saturday and Monday. Barletta will face state Rep. Jim Christiana in Tuesday's primary.
The Republican winner will face Democratic Sen. Bob Casey, who runs unopposed Tuesday. Casey is one of 10 Senate Democrats running in states Trump won in 2016.
Still, he has clobbered Barletta in fundraising. Pennsylvania is also more purple than red: President Barack Obama won the state in both 2008 and 2012.
Nonpartisan handicappers rate every congressional seat in Oregon and Idaho as safe for either Democrats or Republicans. Only one district, Idaho's 1st, will not feature an incumbent running.
GOP Rep. Raul Labrador chose to run for governor of Idaho instead. A crowded field competes for the GOP nomination, and the winner is all but assured to win the congressional seat in November.
Leading candidates include former state Sen. Russ Fulcher and former Idaho Lt. Gov. and Attorney General Dave Leroy.
Labrador competes in a field of several candidates seeking the GOP nomination for governor on Tuesday.