(CNN) House Ways and Means Chairman Richard Neal is not backing down on his request for six years of the President Donald Trump's personal and business tax returns, he writes In a new letter sent Saturday to IRS Commissioner Charles Rettig.

In a two-page letter, Neal writes that he believes his committee is well within its rights to see the President's tax returns and that he expects a decision from the IRS within the next 10 days.

"I expect a reply from the IRS by 5:00 p.m. on April 23, 2019. Please know that if you fail to comply, your failure will be interpreted as a denial of my request," Neal writes.

The letter leans heavily into the committee's legal rational for the returns and Neal writes that, "I am aware that concerns have been raised regarding my request, and the authority of the committee. Those concerns lack merit. Moreover, judicial precedent commands that none of the concerns raised can legitimately be used to deny the committee's request."

Treasury Secretary Steven Mnuchin on Saturday said he has "not personally spoken" to Attorney General William Barr about a congressional request made by Neal for Trump's tax returns.

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