Democrats are doing everything they can to get President Donald Trump's tax returns, which they've been clamoring for over the past two-plus years. But their own frontrunner for the 2020 nomination, Sen. Bernie Sanders (I-Vt.), is taking his time releasing his tax returns to the public.

Why should it matter? First of all, Sanders himself has called President Trump out for not releasing his tax returns. To not do so himself would be hypocritical.

During a recent appearance on "The Daily Show," Sanders told host Trevor Noah that he would be "delighted" and "proud" to release ten years of his tax returns, hinting at a potential April 15 release, saying "Hey Mr. Trump, you do the same thing."

But, as CNN's Chris Cillizza points out, Sanders back in February said he would be releasing them "sooner than later"—and we're still waiting.

Secondly, Sanders is running on a socialist platform that often includes him calling out the wealthy in the United States for contributing to economic inequality.

That creates a significant interest in seeing what Sanders' own finances look like, to see whether there is any contradiction apparent between his own life and his political platform.

It's not just Republicans or political opponents asking about Sanders' tax returns. Liberal media is starting to ask questions. In addition to Cillizza's piece "Why is it taking Bernie Sanders so long to release his taxes?" The Intercept takes a harsher tone toward the issue, with Ryan Grim writing that "The Reluctance of Bernie Sanders to Release His Damn Tax Returns is Part of a Bigger Issue."

What do we know about Sanders' finances? From what we know already, Sanders has earned more than a million dollars each of the past few years, owns three homes, and spends hundreds of thousands of dollars on air travel despite his support of the Green New Deal, which calls for a reduction in air travel to reduce carbon emissions.

Hot Air's Karen Townsend sums it up succinctly:

Bernie's living much more like a capitalist than he is a socialist. He's the worst kind of limousine liberal. The April 15 deadline is one he imposed on himself. He is trying to keep pace with the other candidates who have released their tax documents. Never mind the average voter, the other candidates can't wait to get their eyes on his tax reports.