(CNN) Sen. Bernie Sanders will face a smaller field of competition for the Democratic president nomination in his home state next year.

Vermont's secretary of state announced Tuesday that New Jersey Sen. Cory Booker , Colorado Sen. Michael Bennet and former Maryland Rep. John Delaney will not appear on the ballot for the March 3 presidential primary in the Green Mountain State.

"They never filed with our office to appear on the ballot," Eric Covey, chief of staff to Secretary of State James Condos, told CNN.

Booker campaign spokesperson Julie McClain Downey told CNN the campaign was focused on using its resources "in the most efficient and effective way possible."

"In this case, given Vermont's 15% threshold requirement to receive delegates, we have decided to direct our efforts elsewhere to best achieve our goals and objectives," McClain Downey said. Under rules for all Democratic primaries and caucuses, candidates must hit 15% or more to receive delegates at the district or state level.

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