Former New York City Mayor and presidential hopeful Mike Bloomberg (center) laughs with Portland Mayor Kate Snyder and former U.S. Rep. Mike Michaud during a photo op inside Becky's Diner on Commercial Street in Portland in January.

AUGUSTA, Maine — Former New York City Mayor Michael Bloomberg has hired 20 staffers to build up a likely unprecedented operation in Maine ahead of the Democratic presidential primary, while two New England senators have organized here for months.

Eight active candidates will be on the March 3 ballot in Maine, but only three — Bloomberg, Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders — have offices and paid staff in the state. Former Mayor Pete Buttigieg of South Bend, Indiana, has signaled a ramp-up next week with already less than two weeks before Election Day.

Bloomberg, a billionaire who has pumped hundreds of millions of his own money into his presidential run, has established the largest campaign infrastructure of any candidate in Maine and visited the state last month. He hired 20 staffers here and recruited “almost a hundred” volunteers, according to Zachary Holman, Bloomberg’s spokesperson in Maine.

The campaign has also opened three offices in Scarborough, Bangor and Lewiston, with a fourth coming soon in York. Bloomberg has said he will keep offices open to support Democrats through November whether or not he is the nominee. His total level of Maine spending is unclear, since updated campaign finance reports are not due until later this month.

Bloomberg is not competing in any state prior to the so-called “Super Tuesday,” when he is banking on a strong performance in Maine and the 13 other states voting March 3. He has dominated ad spending in Maine with $1.6 million to date, according to FiveThirtyEight. The others have put up another $1.1 million between them, led by Sanders at $750,000.

Warren was the first presidential candidate to hire staffers in Maine when she opened an office in Westbrook last fall. Her campaign said the office was part of an effort to target states with competitive down-ballot races, such as Maine’s 2020 U.S. Senate contests. The Massachusetts senator is looking to Maine after a fourth-place finish in New Hampshire this week.

Sanders visited Maine in September and opened a Portland office in December. His campaign has been active with phone banking and canvassing as the Vermont senator looks to repeat his convincing 2016 win in the Maine Democratic caucuses with more candidates in this race.

Maine has attracted less attention than other states in part because it is one of the smallest states holding its primary on Super Tuesday. While 24 pledged delegates are available in Maine, there are 415 California and 228 in Texas. Delegate allocation is proportional, though candidates must win at least 15 percent of votes to be considered viable.

There is still time for other candidates to build up Maine campaigns. Buttigieg, who visited Portland in August and narrowly won the Iowa caucuses over Sanders before the Vermont senator nipped him in New Hampshire, has yet to set up an office in the state. His campaign said Thursday it had more than 100 volunteers in Maine.

Hawaii Rep. Tulsi Gabbard, a long shot after winning just 3.3 percent of the vote in New Hampshire, will hold events in Portland and Hallowell this weekend.