Washington (CNN) Democrats have control of the House, but that may not be enough to get them one thing they really want: access to President Donald Trump's tax returns.

First as a candidate and now as President, Trump has steadfastly declined to follow his predecessors' example by releasing his tax returns, leaving details of his business dealings and personal wealth shrouded in mystery.

With Trump's lawyers threatening a court fight over the release of the returns, Democrats are expected to go directly to the Internal Revenue Service and demand the documents under an obscure law -- a move that may not guarantee quick results.

The law specifies that the leaders of the House and Senate tax-writing committees each have the power to request taxpayer information and states that "the secretary shall furnish such committee with any return or return information specified in such request."

Yet the unprecedented nature of such a request, combined with the political drama surrounding Trump's returns, would likely draw extended legal review from the Treasury Department.

Read More