No matter how many times President Donald Trump and his allies declare the opposite, Special Counsel Robert Mueller’s report is not "complete and total exoneration." Mueller says this plainly: “While this report does not conclude that the President committed a crime, it also does not exonerate him.”

On the contrary, the 448-page report Russian meddling in U.S. elections lays out in exhaustive detail how Trump possibly obstructed justice while failing to protect this nation against a grave attack on our election system by a foreign adversary.

Mueller writes that, despite many contacts between the Trump campaign and Russians in 2016, he could not establish a conspiracy between them. And he writes that he did not believe it his job to bring criminal charges on obstruction of justice.

For that, it’s up to Congress, whose members, all 535 of them, swore to uphold and defend the Constitution. When a president allegedly violates his own oath to do the same, Congress has a duty to act.

Nancy Pelosi, the shrewd House speaker, is right to be leery of jumping into impeachment proceedings for the perfectly sound reason that, such a perceived rush to judgment would surely be seen as a purely partisan attack that would only further divide an already fractured nation.

That's not what the American people need. What they need are clear answers. The Mueller report lays out a road map for further investigation, but there are gaps to be filled. And the special counsel all but beseeches Congress to pick up the trail. "Congress," the report states, "has authority to prohibit a President's corrupt use of his authority in order to protect the integrity of the administration of justice.”

The president's supporters are correct that for some Democrats, congressional investigations -- about a half-dozen -- will be partisan fishing expeditions. But it is also hypocritical to act as though partisanship didn't motivate similar, costly Republican probes of the Obama administration.

Thus, Democratic leaders in the House of Representatives are doing absolutely the right thing in pressing for investigations, and requesting -- when necessary, subpoenaing -- records and witness appearances to put the facts squarely in front of the American people.

That Trump has responded by refusing every single request shows that the obstruction described in the Mueller report is continuing to this day. And it shows, if any proof were needed, that the excuses Trump has given since 2015 for hiding his tax returns -- documents needed to ensure that his motives as president are to serve the country, not his ample personal interests -- are pure hooey. He simply doesn’t want Americans to see them, not even the chairman of the House Ways and Means Committee whose right to inspect anyone’s tax returns is guaranteed in a 1920s law born of the Teapot Dome scandal.

The fact that Mueller’s report brought no new indictments does not mean no crimes were committed. From the report’s first sentences, Mueller makes clear that he was bound by the Justice Department policy that a sitting president cannot be indicted. Therefore, Mueller says, he wouldn’t even attempt to accuse the president of a federal crime, because, there being no possibility of a trial, the president would have no chance to defend himself -- and this wouldn’t be fair to the nation’s chief executive. (A strange way, you must admit, to conduct a witch hunt.)

So, if the president can’t be indicted, why undertake the $30-million, 500-witness, 1,100-footnote investigation at all? Because, Mueller says, it is important to document as much material as possible while memories are fresh. He says that the president won’t be in office forever; he might have done things for which he could be charged later. And while the Justice Department’s hands are tied now, Mueller makes a point of saying that Congress has every right to step in.

The report documents extremely troubling facts; if they fail to shock, it’s only because the overall story is so familiar. On the very first page, Mueller states: “The Russian government interfered in the 2016 presidential election in sweeping and systematic ways.” The Kremlin ran “a social media campaign designed to provoke and amplify political and social discord in the United States” that reached 126 million Americans on Facebook alone. And this adversary employed a small army of hackers to steal materials damaging to the Hillary Clinton campaign.

This is a serious crime against the United States and the great gift we have inherited of representative democracy.

Trump, as everyone knows, has denied there's any problem or that the Russians were even involved -- when not openly welcoming the Russians’ hacking help. And, as detailed in the report’s Volume II, Trump undertook no fewer than 10 efforts to obscure or derail the investigation into the Russian interference. In four of those cases, possibly five, Mueller indicates that the evidence rises to the legal definition of obstruction.

The cries of “No Collusion!” hardly mean “case closed.” We still must deal with the reality of Russian interference in our election system -- which is bound to occur again in 2020.

And which hits close to home. According to the Mueller report, the FBI believes that Russian military intelligence gained access “to the network of at least one Florida county government.” (Authorities have not identified the county. Palm Beach County Elections Supervisor Wendy Link, like her predecessor Susan Bucher, said it wasn’t Palm Beach County. The FBI has refused to comment.)

We must also deal with the cumulative evidence of Trump’s possible obstruction of justice -- a serious enough crime to lead to articles of impeachment against both Bill Clinton and Richard Nixon.

Whether or not Trump had collusion to hide, he had reasons to derail the Mueller investigation. Foremost among those: his ego. According to witnesses in the White House, Trump could not abide a determination that the Russians helped him win, for that would cast doubt upon his legitimacy as president.

Pelosi is taking perhaps the smartest approach possible just now. The veteran lawmaker is a savvy pro who is walking a tightrope between political calculation and constitutional responsibility. But, ultimately, what must win out is Congress’ responsibility to the Constitution and to the proposition that no one is above the law. Democrats who were elected in part to put a check on Trump, and as many Republicans as have the guts to put country over party, must move boldly.