Rising inequality “is the defining issue of our time,” said President Obama in his Osawatomie speech that echoed the “New Nationalism” address Theodore Roosevelt delivered in that same Kansas town a century ago.

In the last two decades, the average income of the top 1 percent in the U.S. has grown by 250 percent, bemoaned our populist president, while the income of the average American has stagnated.

“This kind of inequality—a level we haven’t seen since the Great Depression—hurts us all,” said Obama.

“Inequality … distorts our democracy. … It gives an outsized voice to the few who can afford high-priced lobbyists … and runs the risk of selling out our democracy to the highest bidder.”

But is the president, a former disciple of radical socialist Saul Alinsky, truly serious about closing the inequality gap?

Or is this just political blather to frame the election year as a contrast between Barack Obama, champion of the middle class, and a Republican Party that supposedly hauls water for the undeserving rich?

Obama’s retort to those who say he is waging class warfare?

Republicans alone prevent him from raising the top U.S. income tax rate from 35 to 39.6 percent, where it stood under Bill Clinton, and advancing America toward true equality.

Republicans reply that the top 1 percent of U.S. taxpayers already carry 40 percent of the income tax load, while half of the nation and a majority of Obama voters pay no income tax at all. Moreover, these free-riders also consume almost all of the $900 billion the nation spends annually on Great Society programs.

Yet, a path has just opened up to test the seriousness of the president, to determine if he is a phony on the inequality issue, or a true egalitarian eager to close the gap.

That opportunity comes from a report last week that income inequality in America is at its greatest in the electoral precinct where Obama won his largest majority: Washington, D.C.

In Washington, the top 5 percent of households have an average income of $473,000, highest of all of the 50 largest cities in America. The average income of the top 20 percent of district households is $259,000. Only San Francisco ranks higher.