PORTLAND, Maine — Republican Sen. Olympia Snowe’s abrupt exit from the Senate race has left candidates flat-footed when it came to raising money needed for the primary, now just two months away.

Federal campaign disclosures suggested there’s no clear leader among the six Republicans and four Democrats but the ground game could be more important than big budgets in determining which of the major party candidates faces independent former Gov. Angus King on the November ballot, some observers say.

To be a primary contender, Republicans generally need at least $125,000 to $150,000 — a level reached by several candidates — but a grass-roots campaign will be more critical because there are so many candidates and a relatively short window between now and June 12, said state GOP Chairman Charlie Webster.

“This election will be won on the ground, mainly because of the short time frame. Olympia getting out means there’s really no time to spend months building an organization,” he said.

Reports filed with the Federal Election Commission last week indicated none of the U.S. Senate candidates whose reports were available had a huge advantage in terms of cash on hand.

Among Republicans, the quarterly disclosures due on April 15 indicated Scott D’Amboise raised the most money by far — more than $600,000 — but he had only $122,738 left through the end of March. Former state Sen. Rick Bennett raised $107,659 and had $104,605 left; Attorney General William Schneider raised $40,095 and had $36,484 left; and Secretary of State Charles Summers raised $21,280, all of which remained.

State Treasurer Bruce Poliquin didn’t have to file during the reporting period, his spokesman said. State Sen. Debra Plowman’s campaign didn’t immediately respond to an email request for her disclosures.

Among Democrats, former Secretary of State Matthew Dunlap raised $56,075 and had $38,907 cash on hand; state Sen. Cynthia Dill raised $24,908 and had $18,032 left; Rep. Jon Hinck raised $41,699 and had $17,091. Portland home builder Ben Pollard has loaned himself $9,000 and has spent more than $6,000 so far on the campaign.

GOP consultant Brent Littlefield, who’s assisting the Bennett campaign, said Bennett’s fundraising numbers are the most solid, especially given the short amount of time in which the money was raised. Bennett, Littlefield said, has demonstrated the ability to raise enough money to go after King.

King, for his part, doesn’t have to worry about a primary but he’s already actively campaigning. FEC filings indicate he has raised $173,561, which includes a loan of more than $37,000 to the campaign.

With primary rapidly approaching, candidates need to get moving, both to raise money for their primary campaigns and to demonstrate that they can pose a serious challenge to King, who has high favorable ratings, said Sandy Maisel, director of the Goldfarb Center for Public Affairs at Colby College.

“If somebody is going to demonstrate that they can challenge Angus King, they have to show that they can raise significant sums of money, and we’re only two months from the primary,” he said.

Mark Brewer, a political science professor at the University of Maine, said the amount of money needed in Maine pales in comparison to campaigns in other states but he agreed that the candidates need to get moving. “There’s a lot of hands to shake and babies to kiss over the next two months,” he said.