Even before the election was called on Tuesday night, the White House had already begun quietly preparing for the investigations that Democratic lawmakers have vowed to launch into the Trump administration and its dealings, according to four current and former administration officials who spoke to NBC News.

The counsel's office has been adding staff and putting in place protocols for the inquiries it anticipates from the Democrats' congressional committees, a White House official said even prior to the results coming in.

Three former Trump officials told the outlet that White House aides, both past and present, have begun hiring lawyers. An administration official and another person familiar with the matter said some ex-officials are turning down chances to return to the White House, fearing they could be caught up in the oversight Democrats are pursuing. The more junior members of the White House staff are not as concerned as the senior aides; one former official put it that Congress may have "bigger fish to fry."

A congressional investigation could carry serious consequences — hence the reluctance of some former Trump officials to return to the administration, according to an administration official and a person familiar with the matter.

With their midterm victories in the House and Senate, the Democrats now have the ability to investigate a Trump administration that has, for the most part, been left largely unexamined by the Republican-led Congress. Once they assume the majority in January, they will be able to issue subpoenas — legally enforceable demands for documents and testimony that can be enforced through the courts — and convene investigative hearings to pursue their answers. Committee chairs direct hearing schedules and subpoena decisions, tools that will shift from Republican to Democratic control in January.

Rep. Robert Garcia, D-Calif., the incoming head of the House Oversight Committee, needed only two words in a statement once the House majority was secured: "Lawyer up."

He was more detailed at a news conference in Huntington Beach, California, on Wednesday. "The reality is there's so much corruption that we have to also really focus on a few key things," Garcia said. He identified four areas his committee — among the House's most powerful investigative panels — will examine come January: the Trump family business; corporate corruption; the late Jeffrey Epstein and those alleged to have conspired with him; and the dealings of former Homeland Security Secretary Kristi Noem along with Corey Lewandowski, a special government employee at the department.

Then there is the question of whether House Democrats will move to impeach Trump, as they did twice during his first term — though the Senate declined to convict him both times. No consensus has emerged among Democrats on a third impeachment. Should the House vote to impeach, 67 senators — a two-thirds majority — would be required for a conviction. Once the final count is in, the Democrats are not expected to hold more than 56 seats in the Senate despite their new majority, a tally that on its own would fall short of the conviction threshold.