Senator Kamala Harris of California dropped out of the Democratic presidential race on Tuesday after months of low poll numbers, a dramatic comedown for a campaign that began with significant promise.

The decision came after upheaval among staff and disarray among Harris’s own allies. She told supporters in an email on Tuesday that she lacked the money needed to fully finance a competitive campaign.

“My campaign for President simply doesn’t have the financial resources we need to continue,” Harris wrote in the email.

The announcement is perhaps the most sudden development to date in a Democratic presidential campaign where Harris began in the top tier. She began her campaign on Martin Luther King Jr Day with comparisons to historic black politicians like Barack Obama and Shirley Chisholm.

Her speech that day in Oakland, California, had more than 20,000 people in attendance, giving credence to the idea that Harris could become the first woman of colour elected President.

But Harris, the barrier-breaking prosecutor and second black woman to serve in the US Senate, was almost immediately overcome with questions about where she fit on the party’s ideological spectrum.

She reversed her position on single-payer health care, removing herself from the Medicare for All bill sponsored by Senator Bernie Sanders of Vermont. She struggled with how to frame her record as a prosecutor, oscillating between defending it against progressive criticism and embracing it in a play for more moderate votes.

Harris also faced questions about her political strategy and her campaign’s organisational structure.