The request is viewed by Democrats as vital first step towards oversight of Trump’s income taxes and business network.

A House committee chairman in the United States has formally asked the Internal Revenue Service (IRS) to provide six years of US President Donald Trump’s personal tax returns in a long-awaited move widely expected to lead to a long court battle with the White House.

The request on Wednesday, in a letter from Ways and Means Committee Chairman Richard Neal to IRS Commissioner Charles Rettig, is viewed by Democrats in the House of Representatives as a vital first step towards oversight of Trump’s income taxes and business network, which some lawmakers believe could be rife with conflicts of interest and potential tax-law violations.

“It is critical to ensure the accountability of our government and elected officials,” Neal said in a statement.

“To maintain trust in our democracy, the American people must be assured that their government is operating properly, as laws intend.”

IRS and US Treasury officials were not immediately available for comment.

Trump defied decades of precedent as a presidential candidate by refusing to release the tax documents and has continued to keep them under wraps as president, saying his returns were “under audit” by the IRS.

‘Under audit for many years’

Trump’s former personal lawyer Michael Cohen recently testified in Congress that he did not believe the president was being audited but may have used the audit claim to avoid the scrutiny that could lead to an audit and IRS tax penalties.

Trump was dismissive of the request but continued to make the audit argument in comments to reporters during a meeting with US military leaders on Wednesday.

“Is that all?” the president asked when told Democrats wanted to see six years of his returns.

“Usually it’s 10, so I guess they’re giving up. I’ve been under audit for many years because the numbers are big and I guess when you have a name, you’re audited. But until such time as I’m not under audit, I would not be inclined to do that.”

Neal based his request on his committee’s oversight jurisdiction of the IRS, specifically its alleged audits of Trump and the extent to which the agency has enforced the tax laws against the president.

Meanwhile, Congressional Republicans oppose Neal’s effort, saying such a move sets a dangerous precedent by turning the confidential tax documents of a US citizen into a political weapon.

“This particular request is an abuse of the tax-writing committees’ statutory authority and violates the intent and safeguards of … the Internal Revenue Code,” Representative Kevin Brady, the committee’s top Republican, said in a statement.