This plan by the Democrats to impeach Trump a second time may have been in the works ever since it became clear he was not conceding. With the Capitol “riot”, they found the perfect excuse to go public with the plan.
Much like the call to the Ukrainian president. They said from day one that they were going to impeach him and just needed a made up excuse. Nadler has already said that they will pretty much dispense with actually impeachment hearings and go right a House floor vote.