(CNN) Sen. Kamala Harris is closing three of her four presidential campaign offices in New Hampshire and has fired all her field organizers in the state as she homes in on her struggling campaign in Iowa, an aide tells CNN.

The California Democrat is closing her offices in Nashua, Portsmouth and Keene. Her Manchester headquarters will remain open, but the staff will be scaled back significantly, with only volunteers left to knock on doors and pass out literature.

"Senator Harris and this team set out with one goal -- to win the nomination and defeat Donald Trump in 2020. To do so, the campaign has made a strategic decision to realign resources to go all-in on Iowa, resulting in office closures and staff realignments and reductions in New Hampshire," said Nate Evans, Harris' New Hampshire spokesman.

The almost abandonment of the first-in-the-nation primary state operations follows a major campaign shakeup announced earlier this week to lay off staff and significantly cut costs for Harris' campaign, the latest sign she is struggling to gain traction in the 2020 race.

According to a memo that campaign manager Juan Rodriguez sent to supporters and campaign staff, Harris will lay off staffers in her Baltimore headquarters, deploy staff from New Hampshire, Nevada and California to Iowa, and cut costs. The moves further commit her to her "all in" on Iowa strategy.

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