For example: On Monday, lawyers for the House Judiciary Committee told a federal court it is essential that grand jury materials from special counsel Robert Mueller’s Trump-Russia investigation be given to House investigators. Why? Because it might help the impeachment effort. “If the House approves articles of impeachment,” the lawyers argued, “relevant grand-jury material that the committee obtains in this litigation could be used during the subsequent Senate proceedings.”

If the Judiciary Committee receives the information, there is little doubt its leaders will work with Senate Democrats to create the impression that there is new evidence so compelling that it absolutely must be included in the impeachment trial. And if Republicans disagree, what are they trying to hide?

Indeed, Schumer and his colleagues have prepared the way to characterize any move to limit the trial’s scope as an effort to hide wrongdoing from the American people. “To engage in a trial without the facts coming out is to engage in a cover-up,” he said Monday.

The bottom line is, Republicans should not believe for one minute that the campaign to remove the president will rely only on the case Democrats have built in the House.