Washington • Let us ponder what the reaction among Republicans and conservatives would have been if President Barack Obama had done what President Donald Trump did on Tuesday:

• Sat down with a dictator whose regime had killed hundreds of thousands of people and who tortures and enslaves as many as 130,000 political prisoners in gulags.

• Set no specific preconditions for the meeting and secured no commitment on human rights nor any firm promise to denuclearize.

• Blindsided allies by agreeing to the dictator’s request to cease “provocative” military exercises with those allies.

• Praised the dictator in lavish terms: “very talented man … wants to do the right thing … funny guy … loves his people … great personality … a great honor … I do trust him.”

But we don’t have to wonder what the reaction would have been to Obama doing such things, because we know what happened when he even floated the idea. In 2007, then-Sen. Obama answered in the affirmative when asked if he would be willing to meet without precondition the leaders of repressive regimes, including North Korea’s, “to bridge the gap that divides our countries.”

His presidential opponent, John McCain, and other Republicans hit Obama near daily for what they deemed “inexperience and reckless judgment.” (Hillary Clinton gave him grief, too.) Later, Sarah Palin, specifically mentioning North Korea, proclaimed the Obama doctrine was “coddling enemies and alienating allies.”

Republican lawmakers criticized the Obama administration for having a “buddy-buddy” relationship with Iran, Sen. McCain (Ariz.) likened Obama’s handshake with Cuba’s Raul Castro to Neville Chamberlain’s handshake with Adolf Hitler, and Sen. Ted Cruz (Texas) condemned Obama for meeting Castro while there were “political prisoners languishing.”

John Bolton, now Trump’s national security adviser, in 2013 mocked the “fanciful” idea “that we could talk North Korea out of its nuclear weapons program.”

The website NowThisNews made a video compilation of Fox News commentators’ thoughts on Obama meeting with repressive regimes. Among them: “Obama likes talking to dictators” (Mike Huckabee), “he would meet with some of these madmen without any preconditions” (Palin), Obama is “going to reach out to these crazy people around the world” (Steve Doocy).

This changed on a dime when Trump was the one proposing such action. Fox personalities dutifully praised a “stunning Donald Trump breakthrough” and a “stunning diplomatic triumph.” Sean Hannity, who said in 2008 that Obama’s inclination to meet with rogues was “one of the most disturbing displays” of inexperience, said this year that Trump’s willingness to meet Kim Jong Un “is a huge foreign policy win.”

As Trump and Kim shook hands for the first time Tuesday night, Hannity proclaimed it “officially” historic, compared Trump to Ronald Reagan, called Secretary of State Mike Pompeo a “rock star” and hosted Trump loyalists proclaiming “peace and progress” and “peace and prosperity.” He dismissed “artificial unrealistic expectations” of Trump’s opponents — that is, the complete denuclearization Trump himself demanded.

What Trump has gotten, at least so far, is far flimsier than the Iran nuclear deal he tore up. Trump, in his news conference after the talks, admitted that his joint statement with Kim does not deal with “verifiable or irreversible denuclearization,” said human rights were discussed only “relatively briefly,” and hemmed and hawed when asked what North Korea gave in return for his concession calling off “war games” with South Korea: “Well, we’ve got, you know, I’ve heard that, I mean, some of the people that — I don’t know. …”

Still, Republican lawmakers filled Twitter with applause emoji for Trump after he did the very thing they denounced Obama for even suggesting. Senate Majority Leader Mitch McConnell (Ky.), like many colleagues, called the meeting a “major step” toward peace.

Democrats, were they inclined to be demagogic, could have attacked Trump for sitting down with a murderous dictator. Most didn’t. Though critical of Trump’s deference to Kim and the meeting’s lack of substance, they generally didn’t criticize the idea of meeting.

Senate Minority Leader Charles E. Schumer (N.Y.) reflected the tone of many Democrats when he said “we remain supportive of American diplomatic efforts,” while noting that if a Democratic president did what Trump did, “the entire Republican Party would be shouting grave warnings about the end of American leadership and the belittling of our country.”

This points to the asymmetrical partisanship in our current politics: Republicans are blithely hypocritical in praising Trump for doing the same thing they blasted Obama for suggesting, but at least some Democrats retain enough integrity not to dismiss diplomacy just because it is being attempted by their opponent.

Dana Milbank | The Washington Post