After three years, we're still on the Russia story.

To be sure, the locus has shifted 500 miles west from Moscow to Kiev, and now we are consumed with the Ukraine controversy rather than the Russia investigation, although it's essentially the same thing - a battle over President Donald Trump's legitimacy fought out with allegations of foreign interference.

The effort to widen out the Ukraine controversy, from the core of it - Trump's mention of the Bidens on his call with Ukrainian President Volodymyr Zelensky - to his urging Ukraine, Australia and others to cooperate with Bill Barr's investigation of the origins of the Russia probe, illustrates the point nicely.

There's nothing wrong or unusual about a United States president asking foreign leaders to provide information useful to his attorney general in a duly constituted investigation. Why would there be? Except the president's detractors don't consider Barr's investigation aboveboard; in fact, they consider it another form of Trump's perfidy.

In its report on Trump's call with the Australian prime minister, The New York Times says - in a news report, mind you - that the call "shows the president using high-level diplomacy to advance his personal political interests." Trump is pleased with Barr's investigation. That doesn't make it merely a pet political project, or mean that there isn't a genuine public interest in knowing in greater detail how and why the Russia story got started.

The Times of London reported of Trump's call to British Prime Minister Boris Johnson that he wanted "to gather evidence to undermine the investigation into his campaign's links to Russia." There's not really anything to undermine, though, since the investigation has been over for months. Trump is basically being accused of the entirely new offense of obstruction after the fact.

The Russia investigation figures into the Ukraine story in another way. It's not clear that even Democrats would consider his Ukraine call impeachable if it weren't for their belief that Trump has gotten away with so much previously.

Even the framework of the Ukraine matter reflects the Russia story. Trump's critics say he was asking for Ukrainian "interference" in our elections, when what was really going on was that he and Rudy Giuliani were interfering in Ukrainian politics.

If you accept the premise that any information developed in a foreign country and used in American politics is election interference, then Trump's opponents themselves were masters at it. As Politico reported back in 2017, Ukrainian government officials "helped [Hillary] Clinton's allies research damaging information on Trump and his advisers."

Giuliani's Ukraine adventure was motivated, in large part, by the desire to get to the bottom of this activity in 2016, and turn the tables on Trump's critics.

There will be lots of comparisons to the 1990s as the House moves toward impeachment. Yet the vitriolic politics of the 1790s might be the more apt predicate. Back then, at the outset of the republic, each nascent political party was consumed with the idea that the other was a tool of a foreign power (either France or Britain), and believed that the other was a fundamental threat to American democracy.

Today, the Democrats still haven't gotten beyond the idea that Trump is somehow a tool of Russia, while Republicans point to Democratic coordination with shadowy foreign forces to get the Russia investigation rolling. Books fly off the shelves about Trump being an alleged fascist, and Republicans are gripped by a Flight 93 mentality that fears if they lose a presidential election, they will never win another one again.

The Russia story contributed to and fed off this feverish atmosphere. For the longest time, it offered Democrats the hope of deliverance from a president whose election they never truly accepted. When Mueller didn't have the goods, House Democrats were briefly at sea, until Trump's call and the whistleblower complaint brought impeachment deliciously back into play.

Ukraine is more an epilogue of the Russian investigation than the beginning of a new book.

Rich Lowry can be reached at comments.lowry@nationalreview.com.