It's not particularly noteworthy that a presidential candidate should go to Liberty University, a conservative evangelical college, and deliver a tough critique of President Obama's record. It is unusual when the critique is delivered by a Democratic candidate who's challenging Hillary Rodham Clinton from the left. Yet that's what Sen. Bernie Sanders did on Monday.

Sanders, I-Vt., didn't mention Obama by name in his speech. But he sketched a bleak picture of the country at the tail end of Obama's two terms in the White House.

"In my view there is no justice in our country when youth unemployment exists at tragically high levels," Sanders said. A fifth of children live in poverty, he noted, and the U.S. jails more people than any other country on earth. We have "a rigged economy, designed by the wealthiest people in this country to benefit the wealthiest people in this country at the expense of everybody else."

Sen. Ted Cruz, R-Texas, who launched his own presidential campaign at Liberty, could have delivered parts of Sanders' speech. "Today the top 1 percent earn a higher share of our national income than any year since 1928," Cruz said in January. Sanders said for his part that 58 percent of the income gains from 2009 to 2014 went to the top 1 percent.

Cruz and other Republicans who cite such figures think about inequality differently than Sanders does, of course. Sanders talked about a small number of people who have "huge yachts and jet planes and tens of billions," while others "are struggling to feed their families." Most Republicans would say that an economy that fed all people well would still have yachts — gaudy ones, even — and there's no problem with that. But they would wholeheartedly agree with Sanders that happy days aren't here again.

Even on health care, Sanders offered no credit to Obama. He claimed that thousands of Americans die each year for lack of care, either because they have no insurance or have excessively high deductibles. If the Affordable Care Act has done anything to improve this situation, Sanders didn't think it worth mentioning.

Sanders' ascent in the polls suggests that many Democrats like what they're hearing from him. And what they're hearing is that in year seven of the Obama presidency, the U.S. is a nation of Oliver Twists.

Clinton and Vice President Joe Biden typically offer more praise for Obama and his policies, but they too complain about the economy in ways that typically come from members of the out party. "We're going to go back to enforcing labor laws," Clinton says. Back? Biden says he's mad about how workers have been getting "clobbered."

All of these Democrats are demonstrating the difficulty of campaigning to extend a two-term streak in the White House at a time of economic discontent. Republicans at the end of Ronald Reagan's second term and Democrats at the end of Bill Clinton's could ask to be rewarded for helping to bring about a satisfactory economy (although Al Gore muddled that message and lost the 2000 election partly as a result). The current mood of the country isn't conducive to that kind of campaign, though, and the Democratic candidates know it.

But campaigning as though they're mad as hell about the economy raises an obvious question: If workers are still getting clobbered, what's the point of a third Democratic term?

Republicans don't yet have a policy agenda that answers voters' economic discontent. But the Democratic candidates are helpfully putting some of the premises in place for their eventual argument for the fall of 2016. The Republican nominee will be able to draw on a rich trove of quotes from Democrats about the inadequacy of what they'll call "the Obama economy," and then say that it's time to go in a new direction.

President George H.W. Bush was mocked in 1988 when he appropriated the song "Don't Worry, Be Happy" as part of his campaign to succeed Reagan. Sanders finished his speech by saying that we had to "take on very powerful and wealthy people whose greed, in my view, is doing this country enormous harm."

That's a very different note, and one that ought to sound rather jarring to the Obama White House.