Imagine you're a Democratic voter who'd been cryogenically frozen right before the 2016 presidential campaign got started — right at the end of 2014, say — and got unfrozen just in time to watch Sunday night's Democratic debate on NBC.

The first question you heard the three candidates answer was what they'd do in their first 100 days. Only one of the candidates mentioned climate change as a top priority. That same candidate was also the only candidate who said he'd get the ball rolling on immigration reform in the first days of his presidency.

You might assume this candidate is the liberal favorite — the progressive challenger to Hillary Clinton that liberals were anxiously hoping would materialize a few years ago. You'd be wrong. The candidate is Martin O'Malley, and he's polling so badly that there was some uncertainty over whether he'd even qualify for this debate.

This is the problem facing poor O'Malley. His agenda should, on paper, appeal to a broad swath of progressive constituencies. But if anyone talked about him before Sunday's debate, it was to express hope that he talked as little as possible, so that voters could see Clinton and progressive challenger Bernie Sanders go head to head.

Be awesome if no one asked a question all night of O'Malley. — Jon Ralston (@RalstonReports) January 18, 2016

Sanders and Clinton's "first 100 days" agendas revealed their appeal. O'Malley's revealed an appeal that isn't materializing.

None of the candidates really stuck to the terms of the question: Moderator Lester Holt asked them to name three things they'd accomplish in their first 100 days, and none of them quite managed to stick to three. But their answers, nevertheless, revealed their priorities.

Bernie Sanders stuck to the core economic-populism agenda that has defined his campaign: raising the minimum wage to $15 an hour, guaranteeing health care as a right, and creating jobs with a plan to rebuild American infrastructure, as well as reminding "the wealthiest people in this country that, yes, they are going to start paying their fair share of taxes."

Sanders isn't as single-minded in his messaging as he was at the beginning of his campaign; most notably, he's broadened his scope to appeal to progressives most concerned about racial equality. But the excitement that his campaign has been able to generate — and the reason that he's become the "progressive alternative" to Hillary Clinton in the race — is due to the thesis of his candidacy: The rich own too much of the country, and everyone else needs to take it back.

Clinton, for her part, started off with five different proposals: "plans for creating more good jobs and manufacturing, infrastructure, clean and renewable energy, raising the minimum wage, and guaranteeing, finally, equal pay for women's work." And that was just the first part of her agenda. After going into a few details for expanding health care reform (the second agenda item), she concluded with an interesting final priority:

I would be working in every way that I knew to bring our country together. We do have too much division, too much mean-spiritedness. There's a lot we have to do on immigration reform, on voting rights, on campaign finance reform, but we need to do it together.

You can look at this as a way to stuff in the few progressive wish list items that she hadn't yet mentioned — a typically overambitious, pandering move for a candidate who's long been accused of being both of those things. Or you can see it as a reflection of Clinton's center-left, 1990s-forged politics: Economic issues that affect middle-class white people can be issues of easy consensus, but issues that affect largely nonwhite people — like immigration reform and voting rights — are political uphill battles that need to be approached carefully.

Either way, both Sanders and Clinton's answers gave relatively short shrift to non-economic progressive issues. Martin O'Malley's, on the other hand, gave a broadly progressive answer.

O'Malley also listed a bunch of bills as his "first item" — but emphasized immigration reform among them: "Getting 11 million of our neighbors out of the underground shadow economy by passing comprehensive immigration reform." He was also the only of the three candidates to mention unions, saying he'd propose to make it "easier rather than harder for people to join labor unions" — a reference to card check.

And O'Malley was also the only candidate on stage to say the words "climate change" as a priority for the early days of his presidency. His second agenda item, he said, would be "a plan to move us to a 100 percent clean electric energy grid by 2050 and create 5 million jobs along the way."

Unions, Latinos, environmentalists — these are key Democratic constituencies, as voters, donors, or both. It's not that Sanders and Clinton didn't address issues these groups care about — it would be ludicrous to believe that unions don't care about raising the minimum wage, for example. But O'Malley's answer was both specific in its appeals to each group and broad in containing appeals to all of them.

This isn't the last-ditch effort of a desperate candidate. O'Malley has been enthusiastic about climate change. He has the best record on immigration of any Democratic candidate. The problem is not that Martin O'Malley is not saying the right things. It's that saying the right things has not heretofore been enough.