Donald Trump’s campaign may be failing to reach thousands of voters they hope to turn out in Arizona and Nevada, with roughly a quarter of door-knocks done by America Pac flagged by its canvassing app as potentially fraudulent, according to leaked data and people familiar with the matter.

The potentially fake door-knocks – when canvassers falsely claim to have visited a home – could present a serious setback for Trump as he and Kamala Harris remain even in the polls with fewer than 20 days until an election.

The Trump campaign earlier this year outsourced the bulk of its ground game to America Pac, the political action committee founded by Elon Musk, betting that spending millions to turn out Trump supporters, especially those who don’t typically vote, would boost returns.

But leaked America Pac data obtained by the Guardian shows that roughly 24% of the door-knocks in Arizona and 25% of the door-knocks in Nevada this week were flagged under “unusual survey logs” by the Campaign Sidekick canvassing app.