The Left is impossible to keep up with.

Last week, after President Trump spoke in Poland, he reached out to the European nations he has been so attacked for alienating, and he sang an ode to Western civilization. This, a Washington Post opinion writer told us, was "white nationalist" "dog whistles."

A Vox.com writer Voxplained to her readers that Trump's speech was "an alt-right manifesto."

Extolling Western civilization, our elites tell us, now makes one part of the alt-right.

This is the way you argue if you want to increase the ranks of the alt-right. It's also the way Democrats and the left-leaning media have been fighting for almost a year: take something widely supported on the Right and lump it in with something rare and repulsive.

This "lumping" aims to toxify the whole Republican Party and every conservative idea. The effect, though, is often to make extremism more palatable to more people.

The clearest example of liberal lumping gone awry happened last year. Back in summer 2016, just after Trump took the GOP nomination, Democrats had a different strategy: drive a wedge between Trump and the Right.

"Look, we Democrats have always had plenty of differences with the Republican Party, and there's nothing wrong with that; it's precisely this contest of ideas that pushes our country forward," President Obama said at the Democratic National Convention. "But what we heard in Cleveland last week wasn't particularly Republican – and it sure wasn't conservative."

This was an eminently sensible tactic, given how un-conservative Trump is and that at 37 percent of the country—the largest group—in an early 2016 poll identified as "conservative."

But then something changed. Maybe Democrats saw Trump as dead in the water, the White House was in the bag, and so they wanted to go for the kill and take back the House and Senate. Maybe it was less tactical and more visceral—Obama always hated Republicans, and his base was probably irked by his game of footsie with "reasonable conservatives."

In October, a few weeks before the election, Obama switched from the wedge strategy to the lumping strategy. Obama said Trump was merely the logical nominee for the Republican Party.

"There's sort of a spectrum," Obama said in an Ohio speech, which labeled the GOP one big "swamp of crazy … a whole kind of ecosystem." A few months after arguing that Trump was this drastic deviation from the norms of the GOP, Obama argued that Trump was simply moving into the house the GOP had built. "He didn't build the building himself," Obama said in his witty climax, "but he just slapped his name on it and took credit for it."

At the moment, Ohio Sen. Rob Portman had withdrawn his support for Trump. Obama decided that this moment of party vulnerability was the moment to lump Portman in with Trump, declaring Portman's stance invalid. They're together, Obama argued. Trump and Portman. Portman and Trump.

Portman's agenda in the Senate had been "crazy," Obama argued, "based on lies." And so riffing on Trump's birtherism, dalliance with the alt-right, lying, bragging of sexual assault, Obama said "don't act like this started with Donald Trump…. And that's why we've got to win this election at every level."

If you know anything about Rob Portman, a painfully boring moderate Republican, this is absurd. But you can see the logic behind the tactics — lumping Trump with Portman could bring down Portman. Thing is, the opposite happened. It picked Trump up. Look at the Huffington Post's poll tracker or Real Clear Politics' average. Trump had consistently trailed in Ohio since the GOP convention. In the days after Obama's Portman equals Trump speech, Trump pulled ahead, and stayed there for good.

Ohio voters knew Portman. They supported him. And maybe Obama's argument—Trump's just a more vulgar version of Portman—sunk into the brains of moderate Republicans.

Surely some people thought: oh, when Hillary said "deplorable" she just meant "right of center." When she said "homophobic" she just meant "opposes gay marriage."

Now the Left is up to it again. They think they're cleverly tying Trump's defense of the West to the alt-right, thus defanging any conservative defense of the West. Instead they may be dumbing down the meaning of alt-right, or making it seem more innocuous.

Oh, "alt-right" and "White Nationalist," just means that you love and care about Western civilization? I thought it was something bad.

Liberal lumping half-worked last year. The result may have been President Trump. The lumping they're trying these days is far more pernicious, lumping something far worse than Trump (white nationalism) in with something more crucial than the GOP (the West).

All good people should hope that this time the Left fails completely.

Timothy P. Carney, the Washington Examiner's commentary editor, can be contacted at tcarney@washingtonexaminer.com. His column appears Tuesday nights on washingtonexaminer.com.