When all is said and done, how much will Congress and the public really end up learning about foreign efforts to interfere in the U.S. presidential election?

The sobering answer to this question is: We may not learn very much about what really goes on at all.

Sen. Chris Murphy (D-Conn.) is trying to do something about this. He is urging the administration to declassify a key report detailing the intelligence community’s current knowledge of Russian interference, while protecting sources and methods.

This is unlikely to happen. And this sheds light on a broader problem: the constant habit of presidents and executive branches to abuse classification authority, something President Trump has engaged in, though many others have as well, including former president Barack Obama.

As a result, we may learn very little about what’s really happening — at exactly the moment when it’s becoming more clear that Russia is taking an increasingly active role.

“The mountains of evidence are growing that the Russians are attempting to play a major role in 2020,” Murphy told me. “It’s important for voters to know the extent of the Russian operation.”

Two new developments underscore the urgency of this.

First, the U.S. Treasury Department just slapped sanctions on a Ukrainian lawmaker, Andriy Derkach, who has been pushing Congress to investigate a series of smears about Joe Biden. Treasury bluntly claimed that Derkach is functioning as an agent of a Russian disinformation campaign.

As a quick aside, note that Trump lawyer Rudolph W. Giuliani, a ringleader of the scheme to smear Biden that got Trump impeached, appears to have been working with Derkach on this effort. And Trump’s Senate allies are pursuing a phony “investigation” designed to fake-validate similar narratives.

Second, Microsoft announced Thursday that it has detected signs that the Russian hacking operation that struck in 2016 is again actively targeting political campaigns and parties. Microsoft also said China and Iran are pursuing such activities, but experts say Russia poses a far more serious threat.

Microsoft has also reportedly indicated that hackers targeted a Democratic consulting firm that advises the Biden campaign, and The Post reports that Russia might be laying the groundwork for another 2016-style cybertheft operation. But in truth, little is known about these activities or their intentions.

Which is exactly the point: We don’t know much.

Enter Murphy’s effort. He is trying to get the Office of the Director of National Intelligence to declassify portions of its recent national intelligence estimate that addresses foreign electoral interference.

Murphy recently sent a letter to something called the Public Interest Declassification Board, an independent panel created by Congress to provide neutral advice to the executive branch on declassification decisions.

Murphy said recent classified briefings about ongoing Russian interference provided to him and other lawmakers by intelligence officials convinced him that the public would be alarmed if it had more knowledge of what’s happening.

“People should be very nervous about the size and scope of Russia’s operation,” Murphy told me.

The ODNI recently revealed that Russia is using a “range of measures” to interfere in the election, primarily to damage Biden. But Democrats lambasted this disclosure for revealing far too little, and for drawing a false equivalence with Chinese and Iranian activity that muddied the waters around Russia’s role (as Trump wants).

Murphy says the ODNI could declassify much more of its intelligence on ongoing Russian interference. So Murphy is asking that independent panel to issue an opinion on what the ODNI could declassify without compromising sensitive information.

“I am certain that there are major elements that can be declassified without compromising sources and methods,” Murphy told me, which would provide Americans with “very important detail[s] about the variety of ways that the Russians are attempting to manipulate the election.”

Murphy added that this intelligence, which he’s seen, also goes into detail about “the stories that the Russians are trying to tell about Joe Biden.”

“Voters will be very interested to find out how those stories match up with information that’s coming out of certain corridors of the United States Capitol,” Murphy noted.

Those skeptical about Russian interference would probably point out that Murphy is free to make such claims about Russia’s intentions, secure in the knowledge the intelligence community won’t ever release much that could test those claims. But again, Trump’s own intelligence officials say Russian interference is active and ongoing, and it should be on them to release as much as possible.

This is particularly so, given that they have now suspended in-person briefings to Congress, and that Trump himself has openly invited more outside sabotage.

Even if this outside panel does issue an opinion declaring that extensive declassification would be doable, of course there’s a high likelihood that it won’t happen.

But Murphy points out that this would nonetheless “create additional pressure to release this information,” particularly on intelligence officials “who do see it as their duty to give the public information that will help them make an educated vote.”

Trump could always quash any such release. But at least the public would then be clearly alerted as to his determination to deny us this knowledge.