Sixteen progressive groups have teamed up in a historic and coordinated effort to oust Gov. Paul LePage, outspending his Republican allies nearly 2-to-1 on advertisements, voter mobilization and persuasion efforts.

All told, organizations that can spend an unlimited amount of money have poured more than $8.5 million into the race for governor, according to an analysis of data from the Maine Commission on Governmental Ethics and Election Practices.

The 16 groups that have combined to back the Democratic candidate, U.S. Rep. Mike Michaud – including unions and nonprofit organizations pushing environmental and women’s reproductive rights – have spent $5.2 million, a sum that by itself eclipses the $4 million spent by all independent organizations during the 2010 gubernatorial race.

Meanwhile, Republican- and Democrat-aligned political action committees have spent $1.9 million on dozens of battleground State House contests that will determine which party controls the Legislature. Democratic committees have outspent Republican groups in those races, too, $1.46 million to $418,000.

Taken together, spending by groups that advertise, advocate and influence voters independently of the candidates’ campaigns have spent $10.4 million on State House races and the gubernatorial contest, according to data collected Tuesday afternoon. That’s roughly equal to the annual budget for the Maine Department of Economic and Community Development and about $10.80 for each of Maine’s 958,440 registered voters.

With less than two weeks remaining before the Nov. 4 election, some of the heaviest spending has yet to come. For example, the tax-exempt Republican State Leadership Committee, funded by assorted tobacco, insurance and fossil fuel interests, has yet to spend much money. It poured nearly $900,000 into the 2012 legislative elections, and in 2010 dropped a late $400,000 ad blitz on key swing districts.

The effects, if any, of all the spending are unclear. Despite the crush of activity designed to influence voters, the race for governor has remained close, with LePage and Michaud swapping small but statistically insignificant leads in recent polls. Independent Eliot Cutler, meanwhile, continues to lag in third place. His position is reflected in the meager spending designed to either target or boost his campaign. However, the Maine Republican Party recently launched a mailer campaign touting his positions to Democratic voters, an effort to divide the anti-LePage vote.

The Democratic effort in the gubernatorial race has been countered by the Washington, D.C.-based Republican Governors Association. The RGA and the Maine Republican Party have combined to spend $3.3 million in an attempt to re-elect LePage. Of that sum, the RGA Maine political action committee, tapping money in the nonprofit organization’s general treasury, has spent $2.9 million in Maine. The RGA receives funding from an assortment of interests, including Koch Industries, a multinational corporation involved in several industries, including petroleum refining.

The RGA spending has been matched by two well-heeled environmental groups, The Maine Conservation Voters Action Fund and San Francisco billionaire Tom Steyer’s NextGen Climate, a super political action committee. They have combined to spend $1.8 million. NextGen is active in at least six other states, trying to defeat candidates who dispute the science behind climate change. In Maine it has spent over $660,000 on mailers, robocalls and canvassing operations. It also has coordinated with the Maine Conservation Voters and other groups to mobilize voters.

The voter drive efforts dovetail with those of the Maine Democratic Party, which has beefed up its canvassing operation.

Meanwhile, the Maine Conservation Voters committee has coordinated its television ad buys with Maine Forward to unleash a flood of advertisements and activity opposing LePage, according to ad buy data from the Federal Communications Commission. Together the two political action committees have spent $2 million opposing the governor.

The Democratic Governors Association, the RGA counterpart funded largely by labor interests, has not made direct expenditures on the race, but it has given $1.2 million to Maine Forward. Maine Forward has spent $2.3 million, including $1.4 million on ads, mostly on television, attacking LePage.

Political action committees are allowed to coordinate election activity with one another, but they cannot do so with candidates’ committees.

Maine Conservation Voters is funded by several prominent Democratic donors, including S. Donald Sussman, who has contributed $100,000. Sussman is the majority owner of MaineToday Media, which publishes the Portland Press Herald/Maine Sunday Telegram, the Kennebec Journal and the Morning Sentinel. Maine Conservation Voters also has received $521,000 from the Washington, D.C.-based League of Conservation Voters, the national nonprofit that has directly spent $12.5 million on congressional contests, according to data compiled by the Center for Responsive Politics.

It’s impossible to identify who funds nonprofit groups because federal laws allow the organizations to shield the identities of their donors.

Like the committees aligned with Democrats, the RGA is handling most of the negative advertising in the gubernatorial contest. It has devoted $1.6 million to attacking Michaud with television, radio and Internet advertising.

Political action committees are active in close to 90 legislative races, with the heaviest spending centered on about two dozen swing districts with the potential to determine who controls the Legislature. Overall, the $1.9 million is short of the $3.6 million spent on legislative contests in 2012, but many of the groups are spending in both the gubernatorial and the State House races.

In September, the Press Herald identified about two dozen battleground races based on an analysis of previous election results, voter registration data and past spending trends. So far, those same districts are witnessing some of the heaviest spending by groups using mail campaigns, canvassing and occasionally television ads to influence outcomes.

The most expensive race is Senate District 9 in Bangor, a contest between Democratic Sen. Geoff Gratwick and Republican Carey Weston. Gratwick has been the biggest beneficiary as Democrats attempt to protect the seat. Groups have spent over $200,000 boosting the incumbent’s candidacy, including $167,500 in opposition ads and operations against Weston.

Democrats also are playing defense in Senate District 30, covering Scarborough, Gorham and Buxton, where incumbent Sen. Jim Boyle is challenged by Rep. Amy Volk. Democratic groups are outspending Republicans there $164,597 to $28,000. However, the race has been identified as a target by the well-funded Republican State Leadership Committee, which has yet to put money into it.

Big money also is being spent in several other Senate contests, including the District 7 race between Republican incumbent Sen. Brian Langley and Ted Koffman (total of $192,426), the District 13 race between Democratic incumbent Christopher Johnson and Republican Leslie Fossel ($129,397), the District 21 race between Democrat Nate Libby and Republican Patricia Gagne ($157,180), and the District 25 race between Democrat Catherine Breen and Republican Cathy Manchester ($76,367).

More than 16 House District races have seen independent expenditures of $10,000 or more.