The state's gubernatorial primary has been the subject of much less national attention than a spate of four special elections for House seats and next week's primary in the Virginia governor's race -- in part because polls in New Jersey have shown each party has a clear leading candidate to replace current Gov. Chris Christie.
Murphy, a 59-year-old former US ambassador to Germany during President Barack Obama's administration, led a pack of six Democratic candidates -- thanks largely to the $16 million he loaned his own campaign.
His Democratic rivals included: former Treasury Department official Jim Johnson, state Assemblyman Jon Wisniewski, state Sen. Raymond Lesniak, activist Bill Brennan and Tenafly Councilman Mark Zinna.
Murphy tweeted Tuesday night that he is "truly honored" and "humbled" to win the nomination.
Guadagno, Christie's No. 2 for the last seven and a half years -- also a former federal prosecutor and Monmouth County sheriff -- was expected to secure the nomination.
Guadagno thanked those involved with her campaign in a series of tweets Tuesday.
"Thank you to all those across New Jersey who voted for this great victory!" she wrote. "I'm proud to be our party's nominee for governor!"
"We haven't come this far to only go this far," she said in a second tweet. "Our campaign is stronger now than when we started because of a spirited & hard fought primary."
Guadagno faced state Assemblyman Jack Ciattarelli, Nutley Commissioner Steven Rogers, as well as businessmen Joseph Rullo and Hirsh Singh.
New Jersey's primaries are limited to registered Democrats and Republicans.
The gubernatorial race -- like the one in Virginia -- is of outsized importance as one of the only two statewide contests in the first year of President Donald Trump's tenure in office. The two races are regularly seen nationally as a gauge of the popularity of a new president's performance and how it's affecting that president's political party.
The Garden State is particularly influenced by national politics because it lacks its own major media markets. Instead, most of the state falls into the New York City and Philadelphia markets.
In New Jersey, though, the double blow of Trump's underwater approval rating and Christie's historic unpopularity -- (in December, Quinnipiac University found his approval rating at 19%, the lowest of any governor in any state in more than 20 years of polling) -- have made for a tougher-than-usual atmosphere for Republicans in an already mostly blue state.
More recent polls -- including Quinnipiac
and Stockton University
surveys last month -- found Murphy and Guadagno ahead of their foes.
But the Stockton poll found a largely apathetic electorate in New Jersey, with 85% saying they tuned in to neither the Democratic nor Republican debates.