BRUNSWICK — As a member of the U.S. Senate Select Committee on Intelligence, Maine’s junior senator knows a lot he can’t talk about.

But what U.S. Sen Angus King, I-Maine, could say Tuesday is that “the Russians were involved” in hacking Democratic Party computers and that they intended to influence the presidential election.

“This is an attack on democracy,” King said, and if the country doesn’t address it in a bipartisan manner, then the 2020 election may feature “Republicans, Democrats, independents and the Russians.”

He said the only real defense against the tactics employed by Russian operatives is to make sure the public knows what’s going on and learns to discount propaganda and fake news that’s specifically aimed at misleading voters.

In a long, wide-ranging interview at a Bowdoin College office near his home, the first-term, independent senator discussed everything from the necessity of public hearings on Russian hacking to President-elect Donald Trump’s leadership style.

King said that Trump needs to have a classified briefing with the director of national intelligence, James Clapper, so he can hear the evidence for himself about why 17 federal intelligence agencies have concluded there’s a major problem with what the Russians did.

“It’s very convincing,” and it poses a grave threat to American democracy, King said.

King said he’s spoken with a number of foreign officials in countries that border Russia, including the Baltic states and the Ukraine, and has heard from them about longstanding efforts to undermine their political systems. He said what happened in the U.S. this year is something with which they’re quite familiar.

The senator, who also sits on the Senate Armed Services Committee, said he’s concerned that a rift has developed between Trump and the intelligence community that he is going to need to rely on after he takes office Jan. 20.

“Good intelligence is the backbone of defense,” King said, and it is crucial that the president has confidence in the work done by intelligence professionals who spend $70 billion a year to supply the country with critical information.

“They’re his eyes and ears,” King said. “If you don’t trust your eyes and ears, you’re not going to make good decisions.”

King, who is seeking re-election in 2018, said he thinks Trump is too defensive about what the Russians did during the campaign. He said the issue facing the nation isn’t to question the outcome; it’s to make sure everything possible is done to minimize future problems.

The senator said he can understand why some electors want to hear classified information about the issue before they vote Monday, but he doesn’t think the Electoral College is going to overturn the results of the balloting on Election Day.

King said that he finds his position on the intelligence panel challenging and hopes he will be able to stay on the committee when the newly elected Senate convenes next month. He said it almost always operates in a nonpartisan way and deals with weighty issues in secret with the right approach.

Trying to balance the necessity of providing for the common defense and the public welfare with the freedoms Americans have always enjoyed is both difficult and interesting for King. Calibrating the relationship between competing ideals is often tense, but crucial.

Given that the only political leaders who have any say in a vast array of secret, intelligence-related work are the president and a few dozen Capitol Hill lawmakers, King said he feels a great responsibility.

There are, he said, a lot of “very challenging issues.”

As an independent, King, a former governor, has the choice of which party to caucus with in the Senate. He said he plans to stick with the Democrats, who have treated him well in his first four years.

The main reason, though, is that King is convinced Maine is better off having him lined up with the Democrats because its senior senator, Susan Collins, is a Republican. Both are considered among the more moderate senators from either party.

“Caucusing is just who you have lunch with on Tuesdays,” King said. Besides, he said, Maine is better off having senators in both parties because it gives the state a foot in both camps.

King said he’s glad the Democratic leadership isn’t looking to replicate the GOP’s 2009 decision to try to block President Barack Obama on everything. He said the nation will be better served if its leaders seek common ground on the issues where it’s possible.

He said that he’s sure he can work with Trump and the Republicans on issues related to infrastructure, where he’s angling to expand broadband internet access to rural areas, and trade deals that he thinks have often been hard on working people.

But there will be areas where King doesn’t see room to compromise. For instance, he vowed “steadfast opposition” to GOP talk of trying to turn Medicare into a voucher system.

King said that while he’s open to efforts to fix the Affordable Care Act, he won’t go along with repealing it because he thinks everyone should have health insurance. He said 84,000 people in Maine alone depend on Obama’s signature health care plan for coverage today.

If Republicans repeal it without a plan already agreed on to take its place, “chaos will ensue” for many people, insurance companies and health care providers.

King, who taught leadership courses at Bates and Bowdoin colleges between his jobs as governor and senator, said he sees some important qualities in Trump, especially the president-elect’s ability to understand what the public wants.

But, he said, Trump has to drop his resistance to criticism and learn to embrace dissent from his aides and others.

King said Trump “needs to realize that 50 percent plus 2 million” people cast their votes for his opponent. He has to bring the country together now, the senator said.

King said he hopes for the best.

“I’m a congenital optimist,” King said.