The Republican primary was hotly contested between Julianne Murray, an attorney from Georgetown, and Colin Bonini, a Delaware State Senator from the 16th district and the Republican nominee for the Governor of Delaware in 2016. Murray ended up winning the nomination. Although Bonini won Kent and New Castle counties, the latter of which is home to Wilmington and is the most populous county in the state, Murray won Sussex County, which is the most Republican county in the state and overall had the most votes, allowing her to carry the nomination.