Two Michigan Democrats are locked in a tight battle to earn the nomination in a crucial Senate seat that will be pivotal to the party's chances of retaking the upper chamber in November's midterms.
After a bruising and sometimes bitter campaign, left-wing insurgent Abdul El-Sayed is slightly ahead of the establishment-backed congresswoman, Haley Stevens, with more than 90% of the votes counted.
The primary has underlined divisions over the party's future, with former public health official El-Sayed channelling grassroots frustration with Washington politics and US ties to Israel.
The outcome of this vote could shape the party's direction well beyond Michigan ahead of November's midterm elections.
The open Senate seat is almost a must-win for Democrats if they want to take control of Congress's upper chamber and try to thwart Trump's agenda.
The seat is currently held by a retiring Democrat and the last time a Republican was elected to this Senate seat was in 1994.
But in presidential elections it is one of the crucial swing states – Michigan voted for Democrat Joe Biden in 2020 but Trump in 2024.
Whoever wins the primary will compete against Trump ally Mike Rogers in the midterms on 3 November.
Both Stevens and El-Sayed have been laying out starkly different visions for Michigan and for the country.
El-Sayed, 41, the son of Egyptian immigrants, would be the first Muslim senator in the US, if elected.
He's been endorsed by leading left-wing politicians such as Vermont Senator Bernie Sanders and New York City congresswoman Alexandria Ocasio-Cortez.
El-Sayed has campaigned on issues such as Medicare for All, taxing billionaires, and abolishing US Immigration and Customs Enforcement (ICE).
Polling from the last year suggests healthcare costs remain among the top issues for voters this year, alongside the rising cost of petrol, groceries and housing.
El-Sayed previously told the BBC that if the Democratic Party had more concerns for everyday people "they'd be fighting on the same policies I'm fighting for".
Young supporters in Detroit hold a sign in support of El-Sayed