The race was not so much symbolic of a liberal-moderate divide among the Democrats as a clash between an insider who rose quickly in local party circles and an agitator who made a living from alienating party leaders by showing their commitment to liberals Ideals questioned. Both candidates were solidly liberal in their views on a number of issues, including legalizing marijuana and, in some cases, making college more affordable or free.

External political groups from different corners of the democratic coalition invested heavily in the race. Ms. Turner was backed by leftist environmental interests in support of the Green New Deal; the political group founded by Senator Bernie Sanders and once headed Our Revolution; and two progressive groups, the Working Families Party and Justice Democrats.

Ms. Brown was more likely to support institutional actors and politicians such as the Political Committee of the Congressional Black Caucus; several senior members of the caucus; James E. Clyburn Rep. Of South Carolina, Whip of the Democratic House of Representatives; Hillary Clinton; Jewish Democrats; Cleveland Area Black Churches; and unofficially Marcia Fudge, who vacated this year to become Mr. Biden’s Secretary for Housing and Urban Development and agreed to have her mother appear in an advertisement for Ms. Brown because she needed to remain neutral as a government official.

Democratic leaders in Washington and groups often at odds with the progressive left were concerned that a victory by Ms. Turner, who topped double digits in early polls and initially raised more money than Ms. Brown, could herald a new round of hostilities within the party for the Democrats.

And the establishment hit back hard – to a degree that it has not had in previous struggles when candidates with the support of party activists such as New York MPs Alexandria Ocasio-Cortez and Jamaal Bowman knock out seasoned politicians with little resistance.

This time, while Ms. Ocasio-Cortez and other stars of the left in Ohio were fighting for Ms. Turner, prominent members of the Congressional Black Caucus such as Mr. Clyburn visited the district and implored the people to choose Ms. Brown as someone who was respectful and to be willing to work with fellow Democrats – an implicit criticism of Ms. Turner’s more confrontational style. She was openly criticized by many, such as Mississippi MP Bennie Thompson, who called Ms. Turner a “lonely know-it-all”.

Advertising attacking Ms. Turner’s professionalism and character was ubiquitous in the district in the last days of the campaign. An ad by centrist group Third Way compared Ms. Turner’s political style and tone to that of Mr. Trump, and reiterated a moment on camera when she was struggling for survival during the campaign by making a rough analogy with choosing between Mr. Biden, whom she did not support, and Mr. Trump.