White House press secretary Sarah Sanders said lawmakers are not "smart enough" to look through President Trump's tax returns.

She appeared on "Fox News Sunday" as a battle is being waged over access to Trump's financial records.

"This is a dangerous, dangerous road, and frankly, Chris, I don't think Congress, particularly not this group of congressmen and women, are smart enough to look through the thousands of pages that I would assume that President Trump's taxes will be," Sanders said to host Chris Wallace.

"My guess is most of them don't do their own taxes and I certainly don't trust them to look through the decades of success that the president has and determine anything," she added. "He has filled out hundreds of pages in a financial disclosure form and I think it is a disgusting overreach that they are making when they're not doing this based on policy. And it puts every American who has filled out tax forms in the past — it puts them all at jeopardy. If they can single one, they can single out everybody."

House Ways and Means Chairman Richard Neal, D-Mass., has sent two letters to the Internal Revenue Service in recent weeks seeking six years of Trump's tax returns. One setting a deadline of April 10, and another on April 23, after Treasury Secretary Steven Mnuchin missed the first deadline.

Congressional Republicans argue the request sets a dangerous precedent for that power, while Democrats maintain it’s a necessary oversight of federal tax law, including the extent that the IRS audits and enforces federal tax laws with regards to the president.

Ever since the 2016 campaign, Trump has declined to release his tax returns, citing an IRS audit.

[Related: Democrats will 'never' get Trump's tax returns, Mick Mulvaney says]