The White House counsel's letter to the Speaker and Chairs of the Committees. I am not sure there is a single soundly reasoned statement in this letter.
Not that it much matters, since this is a political document and a political fight. But the WH legal arguments on this are beyond weak. Basically legal gas-lighting.
It is true that there was a House vote in the Nixon and Clinton cases. But that vote wasn't required by the Constitution or due process. It was required under the then applicable House rules. In prior times, the House rules required a vote in order to give House committee chairs the subpoena power. Under long since changed House rules, the committee's now have standing power to issue subpoenas. Which is how/why the Dem-controlled committees have obviously been issuing subpoenas for some time already.
Note that in the Nixon case, House Judiciary investigated and gathered evidence for months before taking the impeachment inquiry vote. House Judiciary also got (thanks to Judge Sirica) the Watergate road map delivered to it from the special prosecutor's grand jury. In Clinton's case, Ken Starr had spent many years investigating before delivering his voluminous report (complete and unredacted) directly to the House. Nixon and Clinton had little input or due process in that part of their proceedings.
The House's current proceedings are most similar to a grand jury investigation process. Which makes total sense since there has not been any prior grand jury or special counsel/prosecutor process with respect to the Uke situation that the House can piggyback on. Grand jury investigations are always one-sided proceedings run by the prosecutor, are conducted in secret, and have little due process requirements (for example, GJ witnesses have no right to counsel).
Quite understandable that the Dems don't want their Uke investigation mucked up by having Jim Jordan bringing in Giuliani to testify about Biden conspiracy theories. Or letting Matt Gaetz subpoena Hunter Biden for questioning.
Trump's due process would primarily come in the impeachment trial in the Senate. Which is very similar to how it works in criminal courts. You have few rights at the grand jury/indictment stage, then you have full due process rights once you move to the conviction/trial stage.
While Trump's legal position is laughably weak, the delay and PR campaign that it enables has obviously worked for him before. The Dem challenge is to keep enough new evidence and voluntary witnesses flowing to keep the story alive and keep moving public opinion (which is the real jury) in their direction.
Boycott stupid. If you ignore the gator troll, eventually he'll just go back under his bridge.