WASHINGTON -- As Special Counsel Robert Mueller investigation of Donald Trump's campaign and administration grinds on, the Democratic-controlled House Judiciary Committee has launched a veritable investigatory blitzkrieg against the president.

Democratic Chairman Jerrold Nadler of New York has dispatched letters to 81 persons of interest for relevant documents and possible personal testimony that could lead to impeachable offenses on grounds of obstruction of justice, abuse of power and criminal corruption.

Any impeachment procedure would start in the House Judiciary Committee, and if the full House approves (by simple majority) articles of impeachment, the Senate would try the case. Two-thirds of the Senate is required to convict.

During the two previous years under Republican control, House Judiciary was essentially a graveyard for Democratic aspirations to move against Trump, as were other GOP-led congressional committees.

Notably, the House Intelligence Committee under GOP Chairman Devin Nunes of California -- a member of Trump's presidential transition team --short-circuited its own inquiry in the wake of his suspicious March 2017 nocturnal visit to the White House.

Now, the Intel Committee in Democratic hands is one of six House committees acting to make up for the failure or refusal of Republicans on Capitol Hill to put Trump and/or his business organization under a microscope.

Nadler has promised "to act quickly to gather this information, assess the evidence, and follow the facts where they lead with full transparency with the American people. ... This is a critical time for our nation."

But the ranking minority member of the committee, Rep. Douglas A. Collins of Georgia, argues that the intensified focus on various allegations against Trump is no more than a heightened hunt for his impeachment. "The scope of the Democrats' race to find something bad on this president is getting more and more concerning," he says.

Many leading Democrats, including House Speaker Nancy Pelosi, however, have counseled their party as the 2020 election approaches to focus instead on their own ambitious legislative agenda. It includes such issues as improved health care, badly needed infrastructure repair and immigration reform.

Regarding Trump's border wall, some Senate Republicans are finally showing signs of mild resistance. Sen. Rand Paul of Kentucky has declared he will be the fourth GOP defector who would vote for a Senate resolution against Trump's national emergency, thus joining all Senate Democrats to oppose it, though short of the two-thirds required to override Trump's expected veto.

The Republicans insist that the House Democrats' call on 81 individuals to produce documents will merely work over the same grounds already thoroughly mined by Mueller, and by other federal prosecutors for the Southern District of New York.

But these committees will hold public hearings, and this promises a wider circulation of their findings that Mueller could effect in the course of his investigation. The potential witness list includes present or former members of the Trump White House, the Trump campaign and business organization, including Trump's sons Donald Jr. other Eric, and his son-in-law, Jared Kushner.

The critical political ramifications of last November's electoral "blue wave" that swept 40 more Democrats into previously Republican House seats are now being more fully appreciated.

As for Trump, while he has said he will cooperate with all the new congressional inquiries, he continues to sing his old refrain of denial of any wrongdoing. "I cooperate all the time with everybody," he said at an unrelated White House event. "You know the beautiful thing: no collusion. It's all a hoax."

Meanwhile, a House Judiciary Committee aide said the new outreach for information might not be the last. The already wide net cast by Nadler could well to ensnare presidential daughter Ivanka Trump. That might be her father's worst nightmare yet.

Jules Witcover's latest book is "The American Vice Presidency: From Irrelevance to Power," published by Smithsonian Books. Email: juleswitcover@comcast.net