President Obama gave remarks on the Dallas shooting that has left at least five police officers dead, while at a summit in Warsaw, Poland, on July 8. (Reuters)

When an awful event like the shooting of police officers in Dallas happens, we inevitably yearn for leaders who will bring us together, bind up the nation’s wounds, unite us all in common understanding and common purpose. And when they don’t, we’re disappointed and decide that a different individual, perhaps like a politician we admired from our youth — Ronald Reagan, Bobby Kennedy, Franklin Roosevelt — could have succeeded where they failed.

Barack Obama is already getting that criticism, and it will surely increase in the days to come. “I think this is a time when real leaders bring people together, he doesn’t split them apart,” said Mike Huckabee, no doubt echoing the thoughts of many Republicans. “And he ought to do for us what Ronald Reagan did after the Challenger disaster. And that’s remind us of what we have in common, not what separates us.”

But here’s the problem. Barack Obama can’t do that. It isn’t that he won’t try (because he will) and it isn’t that he won’t say exactly the things his critics claim he ought to (because he has, and he will). It’s that it is utterly impossible for Obama to open his arms and gather all Americans together in an embrace of unity.

There are multiple reasons why. The first — and you’ll forgive me for sounding divisive and partisan at a time like this — is that his opponents have guaranteed that he would never be able to unite Americans about anything. A healthy chunk of the country, spurred on by their political leaders and media figures, has spent the last eight years becoming convinced that nothing Obama does, no matter the situation or the issue, is ever for admirable or even mundane reasons. Those politicians and media commentators have told their constituents, thousands upon thousands of times, that Obama is not merely wrong or misguided but is literally trying to destroy America. So for them to turn around now and say, “Why won’t Obama bring us together?” takes a truly superhuman level of gall.

Listen to President Obama's full remarks in the wake of two police shootings in Minnesota and Louisiana that killed two black men. (WH.gov)

You might recall how in the immediate aftermath of the attacks of September 11, Democrats effusively praised George Bush for doing nothing more than making a couple of serviceable statements about our collective resolve. The news media immediately filled with paeans to his wise and steadfast leadership, and his approval ratings rocketed past 90 percent, all before he had actually done much of anything. Could you imagine the same thing happening today? Does anyone believe that there is some combination of words Obama could speak now that would cause the likes of Rush Limbaugh, Sean Hannity, and Donald Trump to say, “That was really terrific; I’ve had my disagreements with him in the past, but today my hat’s off to him”? The very idea is laughable.

The second and related reason that it is impossible for Obama to unify us after this tragedy is that it is tied up with race, and there are significant numbers of white people who will always believe that on issues of race, Obama is intentionally trying to set Americans against each other, no matter what he actually does or says. Any reasonable observer would look at his statements about racial controversies and see someone being painfully careful and tentative, struggling to confront the reality of discrimination and racism without offending whites. But for his trouble, he has been cast by his opponents as a racial avenger, some kind of Black Panther using the powers of the presidency to wreak vengeance upon innocent white people.

Republicans have told themselves a story in which the nation was moving toward racial harmony until Barack Obama came into office and immediately began dividing us over race, pitting blacks against whites and tearing the country asunder. And they have been telling their constituents this from the moment he took office. No one familiar with conservative media can deny that it has featured a festival of race-baiting since 2009, blaming Obama for every racial incident anywhere and casting all his policy decisions as motivated by the desire to stick it to white people. Some black kids beat up a white kid on a school bus? “Obama’s America, white kids getting beat up on school buses now,” Rush Limbaugh, the most popular radio host in America, tells his listeners. “You put your kids on a school bus, you expect safety but in Obama’s America the white kids now get beat up with the black kids cheering, ‘Yay, right on, right on, right on, right on.'” He passes a stimulus bill? “Obama’s entire economic program is reparations,” Limbaugh says. And that was all from his first months in office.

So Republicans have come to believe that they’re the real victims of racial discrimination — or as Bill O’Reilly, the highest-rated host on cable news, puts it, “If you’re a Christian or a white man in the USA, it’s open season on you.” According to a recent poll from the Public Religion Research Institute, 72 percent of Republicans and 81 percent of Trump supporters say that discrimination against whites is as big a problem in America today as discrimination against blacks and other minorities. I won’t spend time explaining how positively deranged this belief is, but if that’s what you think, nothing Barack Obama tells you will convince you that he has your best interests at heart.

Particularly not when whatever he actually says, you can be sure that conservatives will come out right after and insist that he said exactly the opposite. Here’s part of the statement he made about the Dallas shooting:

“Police across America, which is a tight-knit family, feels this loss to their core. And we’re grieving with them. I’d ask all Americans to say a prayer for these officers and their families. Keep them in your thoughts. And as a nation, let’s remember to express our profound gratitude to our men and women in blue — not just today, but every day.”

But if you turned on Fox News this morning, you’d hear the head of a police advocacy group explain how much better it was in the old days when we had a different kind of person in the White House: “I think one of the big differences then was you had governors and mayors and the president — whether it was President Johnson or President Nixon, Republican or Democrat — condemning violence against the police and urging support for the police. Today that’s markedly absent. I think that’s a huge difference, and that’s directly led to the climate that allows these attacks to happen.”

His will be one voice of hundreds from the right, telling people that Obama is doing the precise opposite of what he’s actually doing. Conservatives everywhere will believe it, because they’ve been imbibing those messages for eight years: Obama hates cops, Obama hates white people, Obama is dividing us. Nothing he says on any issue having anything to do with race will persuade them otherwise.

The final reason that President Obama can’t bring us all together is that today’s complex media environment makes it so difficult. There was a time in which something important or tragic would happen, people would gather around their televisions, and everyone in the country would watch as the president (or maybe Walter Cronkite) told us how to interpret what had just occurred. We had only a few streams of information about national affairs, and that created a common text out of which we could come to understand what had happened. Today we construct meaning in a diffuse, dynamic, interactive process. We pick up information from television, from Facebook, from Twitter, all repackaged and reinterpreted along the way. No one, not even the president, delivers the truth to us with the assumption (from either side of the delivery) that we’ll all accept it.

That means that if we’re going to come together as a nation after something like the shooting in Dallas, it won’t happen because the president wanted it to, no matter how eloquent he might be. It’s on us to do it ourselves. I only wish I could believe that we would.