Maine voters should take notice when larger interests pit candidates against one another and overwhelm mailboxes, television screens and radio waves with attack ads. When political action committees and political parties drown out local candidates and their messages, whose election is it?

Look at Bangor. Likely the most expensive Maine Senate race in the state’s history, incumbent Republican Nichi Farnham and Democrat Geoffrey Gratwick have each been pounded by political and personal accusations. But they are not behind the claims. In fact, they have decried them.

To be an informed voter, it’s important to understand who is influencing the local race and why. Seek out independent information to know where the candidates stand on issues; be aware of how ads might make you think differently.

Otherwise, the risk is that the successful candidate will not have won based on his or her own merits but on the half-truths and distortions proclaimed by advertisements paid for by outside forces. So far, the state’s two political parties and some political action committees — which are not allowed to coordinate with the candidates — have spent $414,000, mostly on negative publicity, on the race for Senate District 32, serving Bangor and Hermon.

Making sense of the incredible amount of spending in the Bangor area requires voters to put the campaign in context. It’s a competitive race in a key area of the state. And the tactics being used now worked in 2010.

Two years ago, the out-of-state Republican State Leadership Committee spent $400,000 to support Republicans in five Maine Senate elections, including the Bangor Senate race, and all of the Republicans won. It helped tip the balance of power in the Senate from Democrats to the GOP.

The same tactics are at play now, by both parties: negative ads with ominous music, political fliers with untrue statements. When one side spends, the other must also spend, and it escalates into an arms race. Negativity gets people’s attention quickly. Realize this. Educate yourself.

Remember, the candidates are your neighbors, often with nuances to their views that aren’t captured by political advertisements.

Farnham, for example, said she will support what Mainers decide when voting on same-sex marriage. School choice is “an option,” she said; Maine should comply with the Affordable Care Act; and Maine law adequately addresses abortion. Gratwick says same-sex marriage should be legal; he supports public charter schools, says the state should take advantage of the funding available to expand Medicaid and believes Maine doesn’t need more restrictions on abortion.

If you believe the ads, you’d think Farnham is a rubber stamp for Gov. Paul LePage and Gratwick is “Dr. Taxes.”

Some people might assume that the U.S. Supreme Court’s Citizens United v. Federal Election Commission ruling — which determined that independent political expenditures by corporations and labor unions may not be restricted, based on First Amendment grounds — is behind the flood of money in Bangor. But it’s more complicated, as Maine is one of a few states that has never had a law limiting how much political action committees and parties can spend on state races.

While it’s difficult to directly measure the effect of Citizens United on the Bangor race, there is no doubt that the ruling has caused an incredible increase in the amount of money in American politics. It would be foolhardy to think this larger cultural change won’t affect or hasn’t already affected Maine.

So where is the money coming from? Most of the groups currently spending on the Bangor race are based in Maine but funded heavily by out-of-state interests. To start, the Republican and Democratic parties have paid out far more than either of the candidates, who are limited to spending about $21,000 each because they receive public funding under the Maine Clean Election Act.

Then there’s the Maine Senate Republican Majority PAC, which has funded ads opposing Gratwick. Its largest contributor, chipping in $395,000, is back from 2010: the Republican State Leadership Committee, based in Washington, D.C. The committee’s contributors include Blue Cross/Blue Shield, U.S. Chamber of Commerce, America’s Natural Gas Alliance, Citigroup, Exxon Mobil, Koch Industries and many others.

The liberal Committee to Rebuild Maine’s Middle Class, which has contributed to ads opposing Farnham, is funded largely by unions and other liberal organizations. The committee received about $178,000 from the National Education Association, $146,000 from the Maine State Employees Association and $15,000 from D.C.-based America Votes. Enabled by Citizens United, America Votes formed in 2011 with a purpose to raise funds in unlimited amounts. Its donors include AFSCME, Newsweb Corp. CEO Fred Eychaner and others.

As the money continues to flow, Gratwick and Farnham will, more and more, become pawns thrown about in negative advertising by larger forces intent on grabbing the few votes able to be influenced. Don’t be played.