The Delaware Democratic Party (DelDems) is the affiliate of the Democratic Party in the U.S. state of Delaware. It is headquartered in New Castle County and chaired by Erik Raser-Schramm.

The party is the dominant political party in Delaware and has existed since the Jacksonian Democrats broke away from the Federalists in 1825. Former U.S. President Joe Biden is a Delaware Democrat, having served as a U.S. Senator from the state from 1973 to 2009, when he was inaugurated as vice president. The party also occupies all seats for the state in Congress, all statewide executive offices, and majorities in both houses of the state legislature. Historically a more centrist affiliate of the Democratic Party, the state party has recently become more progressive due to the movement's recent electoral successes against the centrist wing of the party.

As the first state to ratify the United States Constitution, Delaware was at the forefront of the creation in U.S. political parties. The origins of the Delaware Democratic Party can be traced back to the original anti-federalist party. While key difference divide this part from the Democratic Party today, key issues involving government involvement and ideologies such as Jeffersonian and Jacksonian can be linked to modern day ideals of the Delaware Democratic party. Despite being one of the first states with true parties, the spiritual predecessor of the Democratic party struggled to support its agenda in the state. It wasn't until the splitting of parties into federalists and Jacksonians that the Democratic party got its first true start. With only one bad loss in 1855 to the American Party, the Democratic Party dominated politics up until the end of Reconstruction in the United States. Most fascinating of all, was how the party maintained its popularity during the Civil War. Despite being a northern state, Delaware Democrats opposed the abolition of slavery and named themselves "the white man's party" as they fought the Republican congress during Reconstruction. With 36 years of election dominance, the Democrats eventually fell out of power due to the growth of industry in the state.

Following the ousting of the Democrats in both the federal and state sector, the Republican Party remained the dominant party throughout the early 1900s and up until World War II. Even when J. Edward Addicks attempted to illegally purchase the Republican seat in the U.S. Senate, the Democrats were unable to capitalize. From 1897 to 1936, Delaware Democrats held little power in politics with Republicans either dominating the state senate and house of Representatives, or the Democrats completely absent from federal politics. With the power of industry overriding agriculture, the Democratic Party was not able to regain an equal footing in the state until Franklin D. Roosevelt came into office.

Following its period of weakness, the Democratic Party of Delaware began to regain an equal foothold with its Republican rival following World War II. Democrat Elbert N. Carvel served two terms as the governor of the state and helped keep his party relevant when they did not control the state legislature. The Democrats of the late 1970s to 2000 held an equal footing in the state, neither party gaining serious ground on the other. Democrats would end up holding the Governor position in the state for 30 years.

In the 21st century, the Democratic Party has risen to become the most popular party in Delaware. The party has control at the state level over the executive branch and the legislative branch. In 2000, incumbent Democratic Governor Tom Carper defeated Delaware's last Republican United States Senator to date, William Roth, by a 12-point margin. Incumbent Republican United States Representative Mike Castle retired in 2010 to run for U.S. Senate. The seat switched from Republican to Democratic when then-Lieutenant Governor John Carney won the seat that year, which was one of three congressional seats that Democrats gained in 2010.

Preceding the late-2010s, the progressive faction of the Democratic Party held little power in Delaware politics, with the party being primarily dominated by the centrist and conservative wings. In 2018, incumbent centrist U.S. Senator Tom Carper faced an unexpected progressive primary challenge from Dover activist Kerri Evelyn Harris, who received 35 percent of the vote, which was the highest percentage against a statewide incumbent in 20 years.

In the 2020 state Democratic primaries, the progressive movement made unexpected significant gains on the state and local level. The most powerful Democrat in the Delaware Senate, President Pro Tempore David McBride, lost to progressive challenger Marie Pinkney by nearly 5 points. Among other notable wins was progressive Eric Morrison's 22-point landslide defeat of conservative Democratic incumbent state representative Earl Jaques Jr., who faced controversy over homophobic comments he made towards Morrison, who is gay. Other progressive insurgents in the Delaware legislature in the 2020 primaries included Larry Lambert and Madinah Wilson-Anton. Progressive incumbent County Executive of New Castle County Matt Meyer also defeated his significantly funded centrist challenger by 13 points.