A half-hour debate between Republican Bruce Poliquin and Democrat Emily Cain, the candidates running a close race in Maine’s 2nd Congressional District, got nasty quickly Thursday night.

The fourth televised debate of the race, hosted by Bangor and Portland NBC affiliates WLBZ and WCSH, also included independent Blaine Richardson of Belfast, a long shot who often was crowded out in the banter between the party hopefuls.

The claims exchanged between Cain, an Orono state senator, and Poliquin, a former state treasurer from Oakland, weren’t old. He dubbed her a dishonest tax-and-spend liberal, while she dubbed him someone known for “breaking rules to benefit himself.”

In one of the most notable exchanges, Poliquin ducked questions from moderator Pat Callaghan about a controversy that dogged him in office.

In 2012, he was criticized for putting 10 acres of his coastal estate in Georgetown in a state tax-break program meant to encourage commercial logging, which a deed largely restricted. In 2010, he paid $21 in taxes on that plot.

He was never found to have violated any rules and he later moved it out of the program, but criticism has followed. Callaghan asked twice if he acted ethically. He never directly answered.

“I have always paid my taxes, all the time, Pat, in full,” he replied, in a variation of a line he repeated often in the debate.

He pivoted back to Cain as much as possible, going particularly after perceived inconsistencies in Cain’s claims about taxes.

As she has in ads, Cain took partial credit for negotiating a budget with legislative Republicans that passed in 2011. It contained an income tax cut that most Democrats opposed at the time. In a meeting with the Portland Press Herald’s editorial board in 2011, Cain said that her Democratic caucus “hates these tax cuts.”

Poliquin also criticized her for voting for a package of tax changes in 2009 that would have lowered income taxes and applied Maine’s sales tax to scores of services if it hadn’t been repealed by Maine voters in 2010.

He said instead of attacks on his background, her record should be the main issue in the race.

“Why don’t we talk about your record, which is a record of higher taxes, more debt, more welfare and less jobs, and then let’s let the viewers decide who they’d like?” he asked her.

But Cain stood by her record, hitting back at him by criticizing his past reticence to raise Maine’s minimum wage and his support of raising retirement ages for future Social Security and Medicare beneficiaries.

“The problem isn’t that you’ve been successful in business. The problem is that you now want to make it harder for other people in our state,” she said.

Thursday’s hard-charging debate wasn’t supposed to be the last in the race to replace U.S. Rep. Mike Michaud, a Democrat running for governor.

But on Thursday, WMTW, a Portland-area ABC affiliate, canceled its Tuesday debate after Cain told the network she wouldn’t come because Richardson wasn’t invited, sticking to a promise she made at a joint news conference with the independent in July.

A Critical Insights poll of nearly 300 voters released last week put Poliquin five points ahead of Cain with 16 percent of voters undecided.

So Thursday’s closing statements were the candidates’ last appeals on the same stage to try to win that share of the electorate. Cain touted her bipartisan work in the Legislature as an antidote to a divided Congress.

“You can make that choice or a choice of someone who’s just known for breaking the rules to benefit himself,” she said.

Poliquin countered by highlighting his business experience, saying Cain would champion “extreme” policies that would hurt the district.

“But if you want someone to go to Washington and help fix the mess and create jobs, I’m a much better choice,” he said.