AUGUSTA — Democrat Jon Treacy ended his short-lived bid for the U.S. Senate on Tuesday, saying the financial realities of Maine’s high-profile race were “a bridge too far.”

Treacy, who is a retired Air Force major general, had formally announced his plans to seek the Democratic nomination just last month after first signaling his interest in the race in July. But on Tuesday, the Oxford resident announced “with sincere regret” that he was terminating his campaign roughly one week after Republican incumbent Sen. Susan Collins and the presumed Democratic frontrunner, Maine House Speaker Sara Gideon of Freeport, announced they had each raised millions of dollars in recent months.

“Throughout my career I have never had the luxury of ignoring reality and the vast sums of money necessary to fund a competitive campaign are realistically, ‘a bridge too far,'” Treacy said in a statement. “Therefore, I extend my heartfelt thanks to all who have supported me along the way.”

Treacy reported raising $23,718 for the three-month reporting period that ended September 30, which included a $10,000 loan from the candidate to his campaign. He had a cash balance of $26,309, according to filings with the Federal Election Commission. Gideon, by comparison, raised roughly $3.2 million during that same time period and had nearly $2.8 million in the bank. Collins, who has yet to formally announce her re-election bid but is aggressively fundraising for a campaign, received $2.1 million in donations during the past three months and has $7.1 million in cash on hand.

Three other Democrats have also filed paperwork to seek the party’s Senate nomination next year: progressive advocate and lobbyist Betsy Sweet of Hallowell, attorney Bre Kidman of Saco and Michael Bunker of Bangor.

The race is already attracting national attention — and millions of dollars from outside groups — as Collins faces what is expected to be the most difficult re-election campaign of her 22-year Senate career because of her votes on several contentious issues and the nonstop controversy surrounding President Trump. The national Republican and Democratic parties are expected to spend heavily on the Maine race as they battle for control of the Senate.