Tuesday will be a busy day for congressional candidates, with primaries in four states.
No matter what, the first GOP incumbent of the year will lose.
A California Democrat dogged by ethics investigations is facing a rematch from the Democrat he beat two years ago.
And because of California's top-two primary system, which allows the top two finishers in the primary to advance to the general election — regardless of their party affiliation — two Democrats appear headed for a face-off for a Senate seat in November.
North Carolina Rep. Renee Ellmers, a Republican elected in 2010 with tea party support, has been pummeled by outside groups on the right upset with some of her legislative actions on spending, immigration and abortion .
Holding currently represents the 13th District. But because the new district was shifted across the state, he decided to challenge Ellmers in the newly redrawn 2nd District, which includes territory he currently represents. (He actually lives in the nearby 4th District).
Ellmers got a late boost over the weekend with an endorsement from Donald Trump, who recorded a robocall on her behalf. Ellmers is the first congressional candidate the presumptive GOP nominee has endorsed.
Holding has been favored to win. He's spent nearly $400,000 more than Ellmers in the pre-primary period, airing low-budget-looking ads attacking Ellmers.
A third candidate in the race, Greg Brannon, has also been the subject of Holding's attacks and could complicate the outcome if he splits the more conservative vote with Holding. Brannon is a perennial candidate.
Turnout will be low since North Carolina already held its other federal primaries in March. House race primaries were pushed back because of uncertainty over the congressional map. A court appeal of the current map was rejected last week , leaving the new districts in place.
Other incumbents in trouble
Ellmers and Holding aren't the only incumbents who are fighting to hang on Tuesday.
On the West Coast, eight-term California Democrat Mike Honda is trying to fend off a repeat challenge from Ro Khanna, the Democrat he narrowly defeated in 2014's general election.
Under California's jungle primary system, the top two candidates, regardless of party, advance to the general election.
Honda defeated Khanna by more than 20 points in the June 2014 primary. Because Khanna finished second in the four-way contest, he made it onto the general election ballot. Honda won by less than 4 points.
Khanna is back this year, and he's facing a weakened Honda. The Office of Congressional Ethics and the House Committee on Ethics are investigating Honda for mixing congressional and campaign activities.
Both candidates have been raising decent money, although Khanna ended the pre-primary reporting period on May 18 with about $800,000 more in the bank.
After withdrawing $200,000 from his campaign account last year to pay for his legal bills, Honda has since created a legal expense trust fund .
The most crowded primary field this year may be in North Carolina's newly redrawn 13th District, where 17 Republicans are vying for the nomination in the safe GOP seat.
When the General Assembly approved the new congressional map, they also eliminated the state's runoff provision. Since only a majority of the vote is now needed to win, Tuesday's victor will likely win with just a fraction of the votes cast.
The race for California's open 24th District features a much less-crowded field. But with the state's top-two system, the pressure is on for Democrats to ensure at least one of their candidates finishes first or second.
Its current representative, Democrat Lois Capps, announced her retirement last year . She's endorsed Santa Barbara County Supervisor Salud Carbajal, the pick of the Democratic establishment in Washington. Democrat Helene Schneider is also in the running , but she's struggled to raise money.
Republicans Katcho Achadjian and Justin Fareed are trying to make it to the November ballot. Tuesday's primary could yield a variety of combinations: either two Democrats, two Republicans or one of each will make it to the general election.
The jungle primary drama continues at the Senate level, where Democratic Attorney General Kamala Harris is the frontrunner to fill Sen. Barbara Boxer's seat.
Democratic Rep. Loretta Sanchez will likely take the number two spot on the general election ballot as she's expected to outpace the field of Republicans on Tuesday's ballot.
Sanchez's Senate candidacy leaves an open seat in her 46th District that Democrats need to hold.
Democratic take-over opportunities
To make a dent in their 30-seat deficit in the House, Democrats have to knock off vulnerable freshman Republicans in Iowa's 1st and 3rd Districts. Both seats feature competitive Democratic primaries .
GOP Rep. Rod Blum, a member of the House Freedom Caucus, currently represents a district that President Barack Obama twice carried by double digits. The Rothenberg & Gonzales Political Report/Roll Call rates the seat Tilts Democrat.
National Democrats and EMILY's List have backed Monica Vernon , who came in second in the primary two years ago, over 2014 nominee Pat Murphy. A former Republican , Vernon has vastly outraised Murphy, and Democrats think she'd make a strong contrast to Blum.
In southwest Iowa, freshman Rep. David Young will face one of three Democrats in the tossup district. Iraq war veteran Jim Mowrer and businessman Mike Sherzan are locked in a tight primary race , with both campaigns releasing internal polls Thursday showing their respective candidates ahead.
The Democratic Congressional Campaign Committee has not chosen a favorite in this race. The Des Moines Register backed Mowrer Friday for his foreign policy chops and political experience. He lost a long-shot challenge against 4th District Republican Steve King in 2014.
Both candidates ended the pre-primary reporting period with similar amounts of cash on hand, but Sherzan has kicked $643,000 of his own money into his campaign.
Democrats also have their sights set on a much tougher target in Iowa : six-term Sen. Chuck Grassley. GOP opposition to filling the vacancy on the Supreme Court has emboldened Democrats' challenge to the Judiciary Committee chairman.
The national party is behind former Lt. Gov. Patty Judge, but she still needs to win a primary on Tuesday that includes state Sen. Rob Hogg, the early favorite.
Tuesday's other down-ballot races are in New Jersey.
They may be less competitive races, but that didn't stop Obama from wading into one Democratic contest last week with an endorsement of freshman Rep. Donald Norcross.
Norcross, the brother of South Jersey power-broker George Norcross III, doesn't face a serious threat. His 25-year-old primary opponent , Alex Law, is a political neophyte who raised just $16,000 in the first quarter of this year.
Law charges that Norcross has voted against the president on the Iran Deal and Keystone pipeline.
"Donald has been there with me," Obama said in his endorsement.