(CNN) In a preview of the aggressive oversight Democrats plan to unleash in the next Congress, the incoming Democratic chairman of the House Oversight Committee sent more than 50 letters Wednesday to the Trump administration demanding answers about everything from family separations at the border to the Flint water crisis to security clearances and Cabinet secretary travel.

Many of the questions are ones Rep. Elijah Cummings, a Maryland Democrat, has asked before, but the letters have new weight behind them now that Democrats will control the House of Representatives in January and will have subpoena power.

"These are documents that even the Republicans on the Oversight Committee -- at least at some point in time -- believed we needed to conduct effective oversight, but when the Trump administration refused to comply fully, the Republicans would not issue a single subpoena," Cummings wrote in a statement.

"Many of these requests were bipartisan, and some are now more than a year old. As Democrats prepare to take the reins in Congress, we are insisting -- as a basic first step -- that the Trump administration and others comply with these Republican requests."

Reissuing requests for information has been the strategy across several committees on Capitol Hill, a kind of warning of the potential subpoenas to come. Incoming Judiciary Chairman Jerry Nadler has re-sent a whole scope of letters he sent when in the minority on questions related to immigration, white nationalism and the firing of former Attorney General Jeff Sessions.

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