Orono state senator Emily Cain has a $300,000 war chest less than five months ahead of her 2nd Congressional District primary against fellow Democrat Troy Jackson.

Cain’s campaign released new fundraising numbers Wednesday, also giving the Kennebec Journal and Morning Sentinel a summary of a mid-January internal poll showing her leading Jackson, the Maine Senate majority leader from Allagash, among Democratic primary voters in the district by 15 percentage points.

However, about half of the 400 people surveyed by the Cain campaign said they were undecided ahead of the June 2014 primary, which Jackson’s campaign said showed an electorate that’s up for grabs.

“It’s just a long time before Election Day,” said Alan Brewer, Jackson’s spokesman. “I think it’s a very open race.”

Cain and Jackson, along with political newcomer Alden Smith, a former Navy officer from Sangerville, are running for the Democratic nomination for the seat to be vacated by U.S. Rep. Mike Michaud, a Democrat from East Millinocket who is running for governor.

On the Republican side, Kevin Raye of Perry, a former Maine Senate President who lost to Michaud in 2002 and 2012, is squaring off against Bruce Poliquin, the former state treasurer from Oakland. Conservative Blaine Richardson, a former Republican from Belfast, is running as an independent.

Cain’s campaign said she more than doubled her past fundraising haul from Oct. 1 to Dec. 31, the fourth quarter of 2013, raising $157,900. In a Wednesday announcement, the campaign said more than half her money has come from Maine.

“The support that we’ve seen throughout the district is incredibly important and it’s a very strong showing at this point in the game,” said Dan Cashman, Cain’s campaign spokesman.

Fundraising figures aren’t due to the Federal Election Commission until Jan. 31, and that’s when Jackson will release his, Brewer said.

Jackson filed for the race two weeks after Cain, and he was behind in fundraising as of September’s end, when Cain had roughly $143,000 to his $72,000. Both can already tout contributions from top Democratic donors.

Cain has gotten maximum $2,600 contributions from Adam Lee, chairman of Lee Auto Malls, and S. Donald Sussman, majority share owner of MaineToday Media, owner of Kennebec Journal, Morning Sentinel and Portland Press Herald. Sussman is also the husband of U.S. Rep. Chellie Pingree, D-1st District.

Jackson got a $1,000 contribution from high-powered Hallowell lobbyist Severin Beliveau and a maximum contribution from state Sen. James Boyle, D-Gorham.

Brewer didn’t give specific amounts for what to expect of Jackson’s money total, but said he’s not in a money race with Cain.

“I don’t think we ever anticipated matching dollar-for-dollar, but we’re hitting all the milestones we set for our campaign,” Brewer said. “We’re on target.”

Cain’s poll was the first one publicized in the Democratic primary, and Brewer said Jackson’s campaign hasn’t commissioned one yet.

The poll summary showed Cain up 32 percent to Jackson’s 17 percent among likely primary voters, leading among all age groups and by 24 points among women.

After that question was asked, Washington pollster Jill Normington, whose company conducted the poll, said those polled were provided short biographies of each Democratic candidate, including the position they hold and where they live, a question intended to simulate what voters will do when they learn more about the hopefuls.

That question made Cain’s lead expand to a 43 percent to 22 percent margin over Jackson.

Campaigns rarely, if ever, release internal polls that show their candidate down in the race. Brewer wouldn’t comment on the results, but said the summary “doesn’t give you much to go on.”

But Normington, who has worked for Michaud, said she conducted the poll in a conservative manner, guarding against inflating Cain’s numbers. For example, 11.5 percent of those sampled in the poll were from Aroostook County, where Jackson is one of just two state senators.

The total sampled in the county was slightly higher than the share of Aroostook voters in the 2002 primary that gave Michaud his party’s nod. Jackson led there 71 percent to 14 percent, Cain’s poll said.

But that was the only place he led, the poll found. She led by at least 10 points in all other regions surveyed, including a 47 percentage point lead in Penobscot County, much of which she currently represents.

Normington said the poll results were positive signs for Cain, especially as name recognition for both she and Jackson is statisically even. Cain had 42 percent recognition to Jackson’s 38 percent, within the roughly 5 percent margin of error. Among voters who knew both, Cain’s lead expanded, 57 percent to 23 percent.

“What we’re seeing is a lot of momentum and encouraging words from people that not only Emily interacts with, but who people on the campaign interact with,” Cashman said. “Feeling it on the ground is one thing, but seeing it in the numbers is another thing.”

Michael Shepherd — 370-7652mshepherd@centralmaine.comTwitter: @mikeshepherdme