At a lunch with Irish leaders and American lawmakers on March 15, President Obama blasted the Republican party for what he called divisive campaign rhetoric. (Reuters)

In an appearance at the annual Friends of Ireland reception on Capitol Hill, President Obama delivered a stirring condemnation of the climate in the 2016 presidential campaign and called on the country to prove that we are better than the current state of our politics.

Here are the two key paragraphs (Obama spoke for four total minutes):

It's worth asking ourselves what each of us may have done to contribute to this vicious atmosphere in our politics. I suspect that all of us can recall some intemperate words that we regret. Certainly I can. While some may be more to blame than others for the current climate, all of us are responsible for reversing it. It is a cycle that is not an accurate reflection of America and it has to stop. I say that not because it's a matter of political correctness … it's about the way that corrosive behavior can undermine our democracy and our society and even our economy.

In America there aren't laws that say we have to be nice to each other, or courteous or treat each other with respect. But there are norms, there are customs, there are values that our parents taught us and that we try to teach to our children. To try to treat others the way we want to be treated, the notion that kindness breeds kindness. The longer that we allow the political rhetoric of late to continue and the longer that we tacitly accept it, we create a permission structure that allows the animosity in one corner of our politics to infect our broader society. And animosity breeds animosity.

That's powerful stuff -- and marks the third time in the past week in which Obama felt compelled to address the rise of Donald Trump. But, unlike his comments on Friday in Austin at a Democratic National Committee event in which the president was jokingly scornful of the real estate mogul and the party that spawned him, he was far more reflective and serious in his remarks on Tuesday, as he was Saturday during a DNC fundraiser.

Part of that change in tone on Tuesday was that Obama was speaking to a bipartisan group rather than just a bunch of Democrats. But part of it also reflected the events of the past few days -- the cancellation of a Trump rally in Obama's home town of Chicago on Friday night amid widespread protests and a weekend dominated by talk of the rising temperature at rallies for the Republican front-runner. (Obama's speech in Austin came Friday afternoon before any of the events of the weekend had begun.)

Obama's move from jokingly dismissive to serious and concerned reflects a broader transformation in views of Trump by many establishment types over the weekend.  Mocking Trump is out. Shaming Trump is in.

Obama's words won't change a single vote for Trump in the five states casting ballots today. To the extent Obama's remarks have any impact on Trump it will likely be a positive one for the billionaire; being on the receiving end of a scolding by Obama will prove to many Trump supporters that he has gotten under the president's skin. And that will make them happy and confirm for them why they are backing Trump.

Obama, of course, knows that. He's not really trying to keep the Republican nomination from Trump since, well, he couldn't even if he wanted to.  What he is trying to do is provide a counterweight to Trump -- and Trumpism -- that he knows no one else in the political world can do.  Hillary Clinton and Bernie Sanders have condemned Trump, yes, but those rebukes are colored by the fact that they may well face Trump in a fight for the presidency this fall. Obama, on the other hand, won't -- and can't -- run for the nation's highest office again.

Obama's speech in reaction to the events of the weekend was a striking contrast to how Trump responded to those same events. Where Trump shrugged off even the possibility of blame for his role in creating an environment in which fights and the like keep breaking out his events, Obama embraced the communal responsibility for where we are in politics today.

"While some may be more to blame than others for the current climate, all of us are responsible for reversing it," he said. "It is a cycle that is not an accurate reflection of America, and it has to stop."

Those are two very important sentences whether you are a Democrat who voted for Obama passionately twice or a Republican who loathes his policies and believe they have led to a disastrous past eight years.

Obama may not be able to stop -- or even slow -- the increasing vitriol on the campaign trail since embracing that vitriol is good politics at the moment. But, at some point, reclaiming the idea that we can disagree without being disagreeable is something that has to happen.  I don't suspect it will be anytime soon, but leadership is in the trying.