The app grew out of a broader push by Democrats, backed by tens of millions of dollars in donor money, to match the Republicans’ prowess in digital advertising and organizing after the 2016 election. Much of the energy and investment have gone into enterprises that are intended to both boost the Democrats’ digital game and turn a profit, like Shadow.

Yet instead of showcasing how far the Democrats had come since the 2016 defeat, the disarray surrounding the Iowa caucuses raised new questions about how the party hopes to compete in 2020 with the Trump campaign, a digital juggernaut that is churning out ads and raising record sums of money.

“It’s the exact opposite of the Trump team approach — bring the engineers in house, figure out exactly what we need, we build it, we test it, we own it,” said David Goldstein, chief executive of Tovo Labs, a progressive digital consulting firm.