New Jersey primaries arrive with Democrats targeting Republican retirements

When Democrat Phil Murphy won back the New Jersey governor's mansion for his party last September, many nationwide viewed it as the crest of the blue wave speculated to wash over the 2018 midterms.

New Jersey is a state where Democrats control both chambers of the statehouse and where the party has dominated in presidential elections ranging back to 1992. It spent eight years under the leadership of moderate Republican Gov. Chris Christie, but voters' embrace of Murphy's liberal campaign platform – which included calls for marijuana legalization and a $15 minimum wage – appeared to be a harbinger of a shift left for the already blue state.

As a result, Democrats, who already hold seven of the state's 12 congressional seats, are optimistic that they can dominate November's slate and push their number of representatives into double digits. The impending retirement of two New Jersey Republican congressmen has only served to increase Democrats' focus on the midterms.

Here's a look at where the state's seats stand ahead of Tuesday's primary election:

Open seats:

Republican Reps. Frank LoBiondo and Rodney Frelinghuysen have each already announced that they will not be seeking re-election in November. Both representatives were first elected during the "Contract with America" midterms of 1994 – a re-taking of both chambers of Congress by Republicans that Democrats are seeking to emulate in 2018.

While Frelinghuysen did not address the specter of sweeping Democratic gains in November in announcing his retirement and LoBiondo specifically said his decision was "not electoral" and rather could be attributed to term-limits on his positions on two committees, the pair will be joining 45 of their Republican colleagues by stepping away from their House seats – the largest number in one election cycle since at least the early 1970s.

LoBiondo currently represents the 2nd Congressional District, stretching across the southern quarter of the state from the Delaware border to the Jersey Shore, including Atlantic City.

Only once in LoBiondo's 23 years in the House has his Democratic competitor received more than 40 percent of the vote in a general election, but the 2nd district has tilted towards Democratic presidential candidates, voting twice for President Barack Obama in 2008 and 2012. The district was won by President Donald Trump by just over four percentage points in 2016, even as LoBiondo won his race by 22 percent.

Southern New Jersey Democrats have rallied around State Sen. Jeff Van Drew, a dentist by trade who has served in the state Senate since 2008 following six years in the state assembly. Notable Republicans running for their party's spot on the ballot include Hirsh Singh, an engineer who was defeated in a bid for the GOP's gubernatorial nomination in 2017; Samuel Fiocchi, a former member of the state's General Assembly; and Seth Grossman, a former Atlantic City councilman.

Frelinghuysen's 11th Congressional District encompasses a largely suburban area in the north-central portion of the state, an area in which the Frelinghuysen family has long political roots. The congressman's father served 22 years in the House of Representatives and other Frelinghuysen ancestors include U.S. senators, a secretary of state, a vice-presidential candidate and a Revolutionary War soldier.

In the bid to succeed Frelinghuysen, Democrat Mikie Sherrill has attracted the endorsement of former Vice President Joe Biden and former New Jersey Gov. Richard Codey, as well as nearly $3 million in donations and a number of headlines for her varied resume which includes 10 years as a Navy pilot and a stint as an assistant U.S. attorney. Other Democrats on the primary ballot include Mitchell Cobert, Tamara Harris, Alison Heslin and Mark Washburne.

State Assemblyman Jay Webber is the most politically experienced Republican running in the district and has the fundraising edge with over $400,000 raised, as of mid-May, according to the Federal Election Commission.

Competitive races:

A pair of Republican incumbents attempting to hold their seats have taken two decidedly different approaches to their jobs in the 16 months since President Trump's inauguration.

Rep. Tom MacArthur of the 3rd Congressional District emerged as an ardent supporter of the Trump administration's tax reform efforts in the later stages of 2017 despite opposition from a number of Republicans in New Jersey and New York – states with high property taxes in which residents will be disproportionately affected by the legislation's decrease in the state and local taxes that can be deducted from federal income taxes.

Democrat Andrew Kim, a national security adviser to President Obama who is running unopposed in the primary, is likely to campaign against MacArthur's status as the lone New Jersey congressman of either party to support the ultimately successful tax reform bill.

An additional challenge awaits Rep. Leonard Lance in the 7th Congressional District, where the congressman was able to defend his seat in 2016, even as his diverse district, running across the state from urban parts of Union County to rural Hunterdon County, preferred Hillary Clinton to Trump by a narrow margin.

Democrats in the 7th, one of ABC News' "18 for '18" races to watch, include Tom Malinowski, a former assistant secretary of state, and Peter Jacob, the party's general election candidate in 2016. Both Lance and Malinowski have raised over $1.2 million as of May 16.

Other races and candidates to watch:

Sen. Bob Menendez is running for his third full term in office in the aftermath of a federal corruption trial in which he was accused of accepting gifts and trips that went unreported in exchange for favors. In November, a mistrial was declared after the jury could not reach a unanimous verdict and the Department of Justice dropped the charges in January.

Menendez is expected to easily secure his party's nomination, while many of the state's major Republicans, including Lance and MacArthur, are backing pharmaceutical executive Bob Hugin, who has already raised nearly $8 million.

In 2016, Rep. Josh Gottheimer was one of only six Democrats to defeat an incumbent Republican congressman in New Jersey's 5th congressional district. The former 2008 Hillary Clinton presidential campaign adviser will now attempt to defend his seat for the first time in the only Democratic-held district in the state that voted for Trump over Clinton. The president won the 5th district 48.8-47.7.

Garden State political veteran Steve Lonegan, the Republican candidate for one of the state's U.S. Senate seats in 2013, is the favorite to capture the GOP's nomination in the district.

WATCH LIVE TUESDAY: You can watch livestreaming coverage of all the primary action starting Tuesday at 10 p.m. Eastern/7 p.m. Pacific on ABCNews.com or on the ABC News app available on the Apple App Store, Google Play Store, Apple TV App Store, and Roku Channel Store.

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