Donald Trump's stance on presidential candidates has changed significantly over the years. Here's how. (Peter Stevenson/The Washington Post)

Amid the flurry of news about White House news conferences and crowd sizes this weekend, President Trump's top adviser, Kellyanne Conway, said something Sunday that marked one of Trump's first big reversals since taking office: The timeline for release of his tax returns had abruptly shifted from “eventually” to “never.”

Sen. Ron Wyden (Ore.), the top Democrat on the Senate's tax-writing committee, was quick to react:

He, along with Rep. Anna G. Eshoo (D-Calif.), introduced legislation earlier this month to require all sitting presidents and nominated presidential candidates to release their tax returns for the past three years. A Washington Post-ABC News poll released last week suggests that public opinion is on their side: The poll found 74 percent of Americans — including 53 percent of Republicans — think Trump should make the documents public.

The Fix spoke with Wyden on Sunday, hours after Conway made the announcement in an interview with ABC's “This Week.” Our conversation has been edited for length and clarity.

THE FIX: You introduced this bill three weeks ago. How do the dynamics of it change now that the White House says Trump will not release his tax returns?

WYDEN: This, in my view, very much changes the issue, because now it's about a broken promise. The American people were told again and again and again on the campaign trail: “I am going to make them available when the audit is completed.” And I and others went to great lengths to say that was not required — we made it clear that the IRS said you could release your taxes [while being audited]. But the president's rejoinder was always [that] they would be released after the audit.

So today we have a 180-degree break with the pledge that was made to the American people. And it seems now the White House wants to say: “Well, this was all litigated in the campaign.” I don't know of anybody having said the pledge was not going to be valid if the candidate won. So this is apparently the first — or one of the first — major broken promises of the new administration.

UPDATE: In a tweet Monday, Conway reverted back to Trump's talking point that he will release them when they're done being audited without acknowledging her statement Sunday the president would not release them. Richard Nixon released his tax returns while they were under audit.

Right now, your bill is supported by a number of Democrats in both the House and the Senate but exactly zero Republicans. How do you change that?

There have been a number of Republicans who have repeatedly said they want to see a tax return. When the president said nobody cares about this except journalists, [Rep.] Mark Sanford [R-S.C.] spoke out and said, “I do.”

So what we'll be doing now is going back and talking to Republicans who said that the returns should be made public. They didn't take a position on this legislation one way or another. But I think this changes the discussion when you have a broken promise and a break of a 40-year tradition since Watergate.

Even if you get some GOP lawmakers on board, getting this bill signed into law is an uphill battle with President Trump being the one who would sign it.

I think we have a lot of work to do, but political change, it doesn't start at the top and filter down. It's grass roots trickling up, and I think we'll have a lot of Americans interested in this.

They went to the polls in November believing they were going to see his tax returns. I don't think it was an accident that this was one of the first issues that came out in terms of petitions to the White House. It shows there is a lot of citizen interest in this.

The president's lawyer assured us earlier this month that there would be no conflicts of interest between his business (run by his two adults sons) and his presidency. So why focus on tax returns?

During President-elect Donald Trump's first news conference since being elected, his lawyer, Sherri Dillon, says that those who believe that Trump's ownership of hotels constitutes a violation of the emoluments clause are "wrong." (The Washington Post)

The reason that a tax return is so important is this is the baseline in terms of transparency. This is the lowest ethical bar. Before he said he'd clear it after the audits were done, and now he's saying he's not even going to jump.

What I hear you saying is that if the president can't clear this bar of transparency, what can we expect him to be transparent about?

I think that's the question. This really takes the whole issue of transparency in the Trump administration in a very different direction. We've heard that there wouldn't be a blind trust [for his assets]. We have heard that there were various issues with respect to family investments.

Now we've got a full-fledged broken promise. I think, with a broken promise so early in this administration, we can't just pretend this is nothing now, because it will just be the beginning.

If releasing your tax returns is a baseline for transparency, why isn't there already a law requiring presidents/presidential nominees to do it?

This was just a given. This was something that was automatic. There wasn't much question that this was sort of the price of getting to be treated as a serious candidate. If somebody had thought that a serious candidate wasn't going to disclose [his/her tax returns], I think it would have been required at that time.

Should there be different rules for our first president who is a business person, not a politician?

No. I'm sure Jimmy Carter considered himself a business person as a peanut farmer. This is not about your occupation. This is about accountability to the American people.

This is so straightforward. This is something that is the lowest ethical bar. It is baseline financial information.