Independent U.S. Senate candidate Angus King takes the offensive in this ad, which directly challenges his top opponent, Republican Charlie Summers.

The ad marks the start of a more aggressive tack from King, who has been criticized by Maine political operatives for not responding to attacks on his record by national Republican-oriented groups.

• “Charlie signed a no-taxes-ever pledge that’ll make it impossible to solve the deficit.”

This is correct, though we are verifying only that Summers signed the pledge. Whether that act will “make it impossible” to solve the deficit is open to dispute.

Summers was hailed by Americans for Tax Reform, the conservative group led by Grover Norquist, a Republican lobbyist and activist, for signing the group’s terse pledge.

For U.S. Senate candidates, the pledge says the candidate will “oppose any and all efforts to increase the marginal income tax rates for individuals and/or businesses” and “oppose any net reduction or elimination of deductions and credits, unless matched dollar for dollar by further reducing tax rates.”

We rate this statement true.

• “He doubts climate-change science … “

Summers, throughout his campaign, has said he doesn’t believe a main tenet of accepted climate change science — that humans have primarily caused global warming by increasing greenhouse gas concentrations in the Earth’s atmosphere.

At a Portland candidate forum in September, Summers was asked, “Do you accept the scientific consensus that climate change is happening and is being primarily caused by human activities?”

His answer: “No, I don’t. I think that humans certainly have an effect on our environment but I think there are a lot of other natural factors that would be included, whether you’re talking about volcanic eruptions, whether you’re talking about the changes in our atmosphere.”

In a candidate questionnaire, the Bangor Daily News asked Summers, “Do you believe climate change is happening? Do humans contribute to it? What should Congress do to address the problem?” Summers replied, “No, however, we all have a responsibility to be good stewards of the environment.”

Drew Brandewie, Summers’ spokesman, said the campaign’s response to that questionnaire was “a mistake,” and Summers believes climate change “is happening, humans are contributing to it, but there are other factors.”

Because Summers has repeatedly answered “no” to questions asking if humans are the main cause of climate change, it’s safe to say he doubts climate change science. There’s no shortage of sources discussing humans’ impact on climate change. NASA says most scientists agree it’s been mostly caused by humans.

Two surveys, in 2009 from Eos, an American Geophysical Union publication, and in 2010 from a publication of the United States National Academy of Sciences, both showed that more than 97 percent of the most active climate change scientists believe humans have made significant contributions to global warming.

The second study also said “the relative climate expertise and scientic prominence of the researchers unconvinced” of human contributions to climate change “are substantially below that of the convinced researchers.”

We rate King’s statement true.

• ” … favors taxpayer subsidies for big oil, … “

MPBN reported that at the September forum in Portland, Summers said he supported tax subsidies for oil and gas companies.

The Free Press, a Rockland newspaper, reported he said the subsidies “made sense” because they support a fair amount of jobs. The Portland Press Herald said Summers doesn’t support subsidies for alternative energies, like wind and solar power, that aren’t cost-competitive in the free market.

We rate King’s statement true.

• “… and thinks Washington isn’t broken.”

As King, who has made “Washington is broken” a mantra of his independent campaign, says this to the camera, as a quote implied to be from Summers hits the screen: “I’m here to tell you that the system is not broken(.)”

That quote is cited to the Sun Journal, which never put that exact quote in an article about a debate in Lewiston. Summers has essentially said that, but what’s written is a slight misquote: in Summers’ closing statement, he said, “I am here to say to you tonight that the system is not broken. It is rudderless. It is without leadership.”

In his opening statement, he also said something along that line: “There are those who say that the system is broken. I don’t think it’s broken; I think it’s rudderless. I think it’s without leadership.”

King’s campaign could have quoted Summers properly, but that’s our only issue with this statement. King’s point is true. Summers has said he thinks Washington’s system of governance isn’t broken, especially as King defines it.

We rate King’s statement true.

Verdict: King’s ad is honest about Summers’ stances on issues they picked, even though the campaign was sloppy in quoting Summers on what he thinks of Washington’s brokenness. Even that quibble, however, doesn’t make King’s assertion any less true. The other references are spot-on.

We rate this ad true.

Michael Shepherd can be contacted at 621-5632 or at: mshepherd@mainetoday.com