Smoke has been billowing skyward from the Trumpster fire for nearly 100 days – I know, it feels more like 100 weeks – and his refusal to release his tax returns is only stoking the flames.

Basically, his broken campaign promise to release his tax returns (a promise he had voiced repeatedly) is now imperiling his grandiose campaign promise to overhaul a tax system that he supposedly understands “better than anyone who has ever run for president.” He promised to roll out a tax reform plan by February, but two months later, his incompetent motley crew has rolled out nothing.

That’s because they’re not in sync with Capitol Hill because politicians — including a sizeable contingent of Republicans — are wary of passing anything that might wind up enriching Trump. They don’t know what would enrich Trump because they’re in the dark, just as we are, about Trump’s finances. And they’re in the dark because Trump refuses to come clean on his tax returns the way every non-authoritarian president has done since 1976.

More than a dozen Hill Republicans — which is a lot in this era of hyperpartisanship — are calling for Trump to release his tax returns, and even Trump loyalist Joe Walsh, an ex-House member and polarizing rabble-rouser, surfaced on MSNBC with a plea for Trump transparency: “I do think this issue will come back and bite him on the butt.”

It already is. Trump’s fantasy of doing a bipartisan tax reform deal is likely dead unless he releases his returns. Democrats say they won’t cooperate unless or until they have solid assurances that the reform provisions won’t put money in Trump’s pocket. And three Republicans in the conservative House Freedom Caucus have signed onto a Democratic bill that would compel Trump to release his returns.

New presidents are usually at their peak of political influence during their first 100 days. Trump hits the 100-day mark at the end of this month, and he will have accomplished nothing (except to tweet and run his mouth). The travel ban is tied up in court. The overhaul of Obamacare crashed and burned. He needed to kill the Obamacare taxes before tackling broader tax reform. Now he says he might try to re-target Obamacare before moving on to tax reform — but that was just something he said last week, and, as we know by now, his word means nothing.

Trump on ABC News in 2011: “I’m gonna do my tax returns when Obama does his birth certificate … I’d love to give my tax returns. I may tie my tax returns into Obama’s birth certificate.” (One week later, Obama released his birth certificate. In response, Trump said he’d fulfill his promise and release his returns “at the appropriate time.”)

Trump on Irish TV in 2014: “If I decide to run for office, I’ll produce my tax returns, absolutely, and I would love to do that.”

Trump on a radio show in 2015: “I would release tax returns … The answer is, I would do it … I would certainly show tax returns if necessary … I do pay tax, but I’m very proud of what I’ve done. I have no objection to showing any tax return.”

Trump on NBC News in January 2016, signaling imminent release: “We’re working on that now. I have big returns, as you know, and I have everything all approved and very beautiful and we’ll be working that over in the next period of time, absolutely.”

Trump on NBC in February 2016: I’ll release my tax returns “probably over the next few months.”

The good news is that far fewer people are buying his snake oil. According to the latest Gallup poll, 45 percent of Americans see Trump as a guy who honors his promises. Granted, 45 percent sounds high, given his long trail of broken dreams, but that share has dropped 17 points since February. I doubt that this exchange, from Monday’s White House press briefing, will reverse the downward trend:

Reporter: “Is it time to just say once and for all that the president is never going to release his tax returns?”

Sean Spicer: “We’ll have to get back to you on that.”

Does the Trump regime really believe it can overhaul the tax system, with bipartisan support, by stonewalling a broken promise and further destroying the poseur’s credibility? Even his Treasury secretary has told the Financial Times newspaper that Trump’s dream of a summer signing ceremony is “not realistic at this point.”

Or, to paraphrase Trump: Nobody knew that governing could be so complicated.

Dick Polman is the national political columnist at NewsWorks/WHYY in Philadelphia (newsworks.org/polman) and a “Writer in Residence” at the University of Pennsylvania. Email him at dickpolman7@gmail.com.