PORTLAND – The three top candidates in Maine’s closely watched U.S. Senate race clashed over taxes, government spending and negative advertising Tuesday morning during a fast-paced debate hosted by the Portland Regional Chamber.

Borrowing a line from Mitt Romney’s presidential campaign, Republican Charlie Summers accused independent Angus King of supporting “trickle-down government” and criticized the former two-term Maine governor for his willingness to consider potential tax increases.

“You should not be raising taxes on anyone in this economy. That is the quickest way to send this economy further down the line,” said Summers, who also said that regulatory reform and lower government spending would help businesses create jobs.

But King suggested that the Summers anti-tax pledge was unrealistic given the federal fiscal deficit and the gap between revenues flowing into the treasury and funding obligations for everything from Medicaid to highway projects and NASA. King, the current front-runner in the race, has called for reducing spending and closing tax loopholes and has opposed Summers’ call to reduce the tax rate on capital gains.

“I contend that anybody who signed the Grover Norquist pledge can’t even enter the discussion in Washington because everybody knows there has to be additional revenues,” King said, referring to a no-tax pledge by Norquist’s group, Americans for Tax Reform.

Democrat Cynthia Dill, meanwhile, called Summers’ anti-tax pledge “irresponsible” and presented herself as the only progressive candidate willing to fight to end the so-called Bush-era tax cuts for Americans earning in excess of $250,000.

“In terms of the regulation of Wall Street, I think it is perfectly reasonable to ask the people who led our country off of the cliff to contribute,” Dill said.

Tuesday’s debate, which was attended by an estimated 400 people, was the first time that the three candidates seeking to replace Sen. Olympia Snowe have shared a debate stage since Sept. 17. Summers has backed out of several debates in recent weeks, opening him up to criticism from Dill and King. Three other candidates — Andrew Ian Dodge, Steve Woods and Danny Dalton — were not invited to Tuesday’s event.

The tone of the debate was largely cordial, with all three candidates pledging to work across party lines and offering examples of their own bipartisanship in elected office.

But the candidates also sought to differentiate themselves in a race that is attracting national attention and money. Several out-of-state political groups have funneled more than $3 million into the race in recent weeks — with millions more likely on the way — in a sign of the race’s importance in the fierce political battle to control the Senate.

The candidates were asked about the role those outside groups are playing in Maine’s race.

King noted that Summers had rejected his call earlier in the campaign to take a stand against the type of “corrosive” outside spending flooding Maine’s television airwaves with advertising. King had been the target of much of that advertising initially, but has since benefited from ad buys by outside groups.

“It corrupts our politics, but it also makes it hard to work together when you to go to Washington and have to work with someone who has been spending millions of dollars telling lies about you,” King said.

But Summers said spending by independent outside groups was beyond the campaigns’ control. Instead, he attempted to turn the focus back onto King by accusing him of breaking his own pledge not to run negative ads during the campaign.

“Yet he is the only one of the three of us standing up here running negative ads,” Summers said. “And I think that people are tired of politicians who will say one thing and then do another.”

King responded by saying that talking about the differences between himself and Summers isn’t negative advertising. “That’s campaigning,” he said.

Dill noted that she is the only candidate who has yet to benefit from advertising funded by non-Maine political action committees or independent groups. In fact, the Democratic Senatorial Campaign Committee, the Senate Democrats’ campaign arm, began airing ads targeting Summers when King’s poll numbers began falling. Although Dill has the support of the Maine Democratic Party, she has yet to pick up an endorsement from national party leaders.

“What I believe is that regardless of the negativity drowning out our airwaves, that Maine people are not going to be fooled or tricked or deceived into voting for somebody who doesn’t have their interests at heart or who isn’t in touch with their day-to-day lives,” Dill said.

She said the concerns she most often hears out on the campaign trail are job growth, education, access to health care and protecting the environment.

Echoing another theme of the ads against King, Summers said King left Maine with a roughly $1 billion deficit when he departed the governor’s office.

King responded by noting that Maine’s constitution prohibits deficits and, instead, said it was a “structural gap” based on revenue projections that was later closed. He also noted that 10 of the last 11 biennial budgets began with a structural gap.

Washington Bureau Chief Kevin Miller can be contacted at 317-6256 or at:

kmiller@pressherald.com

Twitter: @KevinMillerDC