The story of Russian interference in the U.S. election has become so complex, with so many tangled, cascading developments, there is the risk of becoming overwhelmed and even inured to its significance.

But the recent testimony of former CIA Director John Brennan reminds Americans of the larger issue that cannot be lost sight of in coming weeks and months. The government of Russia, an adversary of this nation for more than 60 years, set out to interfere in this nation's most cherished tradition — the democratic election of its leaders. It sought not just to make mischief, as some originally said, but, in Brennan's words, "to influence resources and authority and power … so that the will of the American people was not going to be realized by that election." That is an act so outrageous, he said, that it is "something that we need to, with every last ounce of devotion to this country, resist."

That is why, as frustrating as it may be to sort through the obfuscations, distractions and misdirection, Americans must keep the pressure on, until the U.S. government deploys all of its resources and authority to determine the full set of facts. This is just as true for Republicans and supporters of President Trump as it is for Democrats and Trump critics. As a people, Americans should be outraged that a foreign government had the temerity to foul a presidential election. They should be frightened that, emboldened by success, those with ill intent could reach further into the daily workings of this nation's government and institutions. Have this nation's citizens become so tribalistic, so suspicious of facts and their government, so comfortable in their ideological cocoons that they are unwilling to face the danger such activities present?

There is still common ground that unites Americans — a love of country and the values so many have died to protect. Let's resist the tendency on one side to leap on every development as evidence of collusion and perfidy. Let's also stop treating the lack of definitive proof as reason to simply stop looking and "move on." A methodical, dispassionate, verifiable examination of the facts must be allowed to unfold.

What is already known is troubling enough. And bit by painstaking bit, journalists keep unearthing nuggets that, while not a substitute for a proper investigation, are daily reminders of the need for one. One recent Washington Post story showed that the Trump campaign relied on cursory Google searches to "vet" volunteers. That brought them Carter Page, a businessman who gained FBI notice as early as 2013 and who, as he became a Trump adviser, was already under surveillance as a possible agent of Moscow.

Michael Flynn, the disgraced former national security adviser fired over his Russian connections, is resisting a congressional subpoena for documents, invoking his Fifth Amendment right against self-­incrimination. Reports allege that Trump himself made private attempts to get former FBI Director James Comey to lay off Flynn, fired him after he declined, and later asked two of the country's top intelligence chiefs to publicly deny evidence of cooperation between his campaign and Russia.

There is no way for Trump — or the American people — to wish this mess away. When foreign interference goes unaddressed, the republic and this nation's sovereignty are at risk. The president still has the chance to hit reset — not by fighting the investigation, but by leading it. By pledging to follow the facts no matter where they lead or whom they implicate, and to do so without interference, obstruction or delay.