With just 48 days to go until the 2016 election, Donald Trump is on course to be the first major party presidential nominee in modern history not to release any of his tax returns.

The reason he and his allies have long given is that Trump is currently being audited by the Internal Revenue Service and it would be inadvisable to release returns under those circumstances. Er, sort of.  The more basic political calculation underlying Trump's unwillingness to release his tax returns is that whatever is in them would do him more damage if made public than the negative publicity he gets for not releasing them.

Now Trump has actual polling data to back up that calculation -- in the form of a new NBC-Wall Street Journal national poll. Voters were asked to choose between a series of potential issues they have with both Trump and Hillary Clinton. Here's what that chart looks like:

Trump's tendency to go over the line when talking about women and immigrants. His temperament. Hillary's emails. Her judgement on foreign policy.  All of those rank as more concerning to people than Trump's tax returns -- or lack thereof.

When people are asked to rank what concerns them most about Trump, his refusal to release his taxes is way, way down the list.

Six percent! That's less than the number of people -- 10 percent -- who say Clinton's health matters most to them. And it's nowhere near the top of what worries people about Trump.

You may argue that people are so worried about HUGE things -- Is he a bigot? Can we trust him with his finger on the proverbial button? -- that big things like his tax returns don't seem to be as large a priority.  And, you will also note that other recent polling on Trump's tax returns seems to contradict the NBC-WSJ finding.  Nearly three-quarters of those polled by Quinnipiac University in an August survey said that Trump should release his taxes; hell, 62 percent of Republicans said it!

But, those two results are not necessarily contradictory.  Sure, people think Trump should release his tax returns. But when it comes to things that truly worry them about the prospect of Trump as president, it's not high on the list. In other words, there's not a ton of urgency from the electorate on the tax returns issue. Sure, Trump should release them but if he doesn't, it's not going to be the single thing that decides whether or not they vote for him.

That reality means that Trump will feel very little need to reverse course on his stated position on his tax returns. Clinton will continue to push the issue and reporters will continue to cover it. But the NBC-WSJ poll suggests that the average person is simply not that motivated by what Trump does with his tax returns.

In other words: Don't hold your breath -- unless you are really good at holding your breath -- waiting on Trump to release his returns before November 8.  It almost certainly isn't going to happen.