President Donald Trump returns to the White House after a flight from New York on Thursday, Sept. 26, 2019. (TOM BRENNER, New York Times/The Minnesota Star Tribune)

In weighing threats to our democracy, it's hard to imagine one greater than political operatives spying on a sitting president and feeding the information to a compliant Justice Department with the goal of destroying him.

Subversion at such a high level is at least as dangerous as a poorly plotted insurrection to the foundation of our nation.

John Durham, the special counsel appointed to investigate the origins of the Russian collusion hoax, says in a court filing that a technology executive working with a lawyer associated with the Hillary Clinton campaign exploited his access to White House and Trump Tower computers before and after the 2016 election.

The sources, the filing says, "enlisted the assistance of researchers at a U.S.-based university who were receiving and analyzing large amounts of internet data in connection with a pending federal government cybersecurity research contract."

The objective, the filing says, was to create "an inference" and "narrative" tying then-candidate Trump to Russia. In doing so, Tech Executive-1 indicated that he was seeking to please certain "VIPs," referring to individuals at Law Firm-1 and the Clinton campaign.

That narrative ultimately took root thanks to efforts by the Clinton campaign, including the Steele dossier, which it funded and directed to the FBI. That information was used to launch an unwarranted investigation into the Trump campaign.

The Russian collusion taint followed Trump into the White House and led to the appointment of a special prosecutor, whose investigation ultimately cleared Trump, but placed a cloud over his presidency.

Durham has already indicted former Clinton campaign lawyer Michael Sussman for fudging the source of information he funneled to the FBI. More indictments are anticipated as his deliberate probe continues.

Dirty tricks have always been part of political campaigns. The most notable was the Watergate scandal that brought down Richard Nixon.

Watergate involved a GOP-orchestrated break-in of the Democratic Party headquarters, and to compare it to what Durham is uncovering is not hyperbole. Mining information from computer systems is today's equivalent to picking the locks of an office to rummage through file cabinets.

Durham's latest filing builds on the earlier indictment of Sussman and the exposure of the shockingly careless use of the Steele dossier. Just because Trump was the target doesn't excuse shrugging off what it means — that Clinton operatives and Justice Department officials worked together in an attempt derail the former president's campaign and then his presidency.

If true, it's an assault on the integrity of the democratic process that will smash public confidence in future elections.

Trump, as always, is distracting from the seriousness of Durham's charges. The former president is calling for the death penalty for anyone convicted of spying on his campaign.

Trump's craziness aside, the issue is the foundational damage done by the efforts of the Clinton campaign and its allies.

Their end-justifies-the-means mentality had a direct impact on the refusal of so many Trump supporters to accept the results of the 2020 election.

Those involved in the alleged espionage plot were doing exactly what Trump is accused of — trying to short-circuit the results of a legitimate election. Their Russian collusion fraud didn't keep Trump out of the White House, but it did limit his effectiveness and erode trust in his presidency.

Democrats and the commentariat class profess shock that so many Trump supporters believe his unsupported claims about the 2020 election.

Why wouldn't they, having seen the extent to which Trump's enemies both inside and outside government went to topple the president they elected?