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.

[3] With 36 years of election dominance, the Democrats eventually fell out of power due to the growth of industry in the state.

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.

In 2000, incumbent Democratic Governor Tom Carper defeated Delaware's last Republican United States Senator to date, William Roth, by a 12-point margin.

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.

The most powerful Democrat in the Delaware Senate, President Pro Tempore David McBride, lost to progressive challenger Marie Pinkney by nearly 5 points.

[6][7] Governor John Carney signed the $15/hour minimum wage bill, but vetoed the legalization of recreational marijuana, for which he was heavily criticized by fellow Democrats.

[8] Progressive County Executive Matt Meyer wrote an open letter to the Delaware legislature encouraging them to override Carney's veto.

Delaware Lieutenant Governor Bethany Hall-Long came out in support of legalizing recreational marijuana following Carney's veto announcement.

[12] In June 2024, both the Delaware House and Senate passed a bill pushed by progressives to abolish the death penalty in statute.

[15][16] In the 2022 elections, progressive former U.S. Senate candidate Kerri Evelyn Harris won a seat to the Delaware House of Representatives.