No sooner did the House vote its articles of impeachment against the President than the Speaker, Nancy Pelosi, threatened to withhold them from the Senate. Her idea seems to be to force the Senate into announcing procedures for its trial that are more to the Democrats’ liking. The scheme was mooted Monday in an op-ed piece by a Harvard law professor, Laurence Tribe, in the Washington Post.

“Impeachment dies in broad daylight” could be the Post’s new slogan. That Mrs. Pelosi may sit on the impeachment became apparent following the vote, in which two articles were passed by House Democrats without so much as a single Republican vote. At a post-impeachment press conference, the Speaker astonished reporters by refusing to commit to transmitting the articles to the Senate.

Mrs. Pelosi’s remarks, Politico reported, were “barely audible above the clatter of camera shutters.” Her words, it added, “were so unexpected that they prompted reporters to shout over each other, interrupting the speaker at times and generating confusion about the next steps in the impeachment process.”

“So you may not send them?” Politico quoted one scribe as shouting in respect of the impeachment articles.

“You’re asking me, ‘So are we all going to go out and play in the snow?’” Politico quoted Mrs. Pelosi as replying. Bizarre.

If the Speaker seemed to be rattled in what ought to be her moment of glory, it could be that she’s suddenly realized the predicament into which she has precipitated the House. If she holds out for a Senate trial that excludes those who are less than impartial or have a personal interest, it could highlight a conflict of interest on the part of such Democratic candidates as, say, Senators Elizabeth Warren, Bernie Sanders, and Cory Booker.

That’s the least of it. House Democrats want the impeachment prosecution to be able to call witnesses. Yet they are talking about witnesses they failed to go after during the proceedings in their own chamber. They plunged ahead without them. Now they are also up against the slab of American constitutional bedrock that establishes that “each House may determine the rules of its proceedings.”

That means that once the impeachment trial is underway, the House has to play by the rules of the Senate. How long it will take Mrs. Pelosi and her camarilla to accept that part of the parchment is hard to guess. It seems to us, though, that every day of delay works to the advantage of President Trump, who is waxing in the polls. That was reported early Wednesday by Gallup’s running survey of presidential approval.

Since the start of the impeachment inquiry, Gallup reported, Mr. Trump’s job approval numbers have notched up by six percentage points, to 45%. We wouldn’t want to make too much of that, but neither would be want to make too little. Maybe it would prove helpful to the Republicans to have Mrs. Pelosi hang onto the impeachment articles for a few months, so that the President can generate more popular support.

Nothing the House can do, after all, is likely to change what we like to call the deep Constitution. It ordains that once the articles of impeachment are approved, the President’s fate is out of the hands of the people, who always lurk in the House. The President’s fate is transferred to the states, which lurk in the Senate and are the very constitutional players who lofted the president to office in the first place.

This is a constitutional concept that the Democrats forgot in 2016. So Secretary of State Clinton campaigned for the popular vote. She got the popular vote she asked for, too, and by a handsome margin. Imagine how she felt when she awoke to discover that the decision belongs not to the people per se but to the states, who were so energetically courted by the man whom they turned into President Trump.

This no doubt helps account for the bitterness that erupted among the Democrats the moment Mr. Trump emerged as president-elect. One could sense that bitterness in the House today. Democrats are still overcome with fury at the deep Constitution that gives the states the power to name as the president the loser of the popular vote. The same Constitution puts the states, absent a reversal of fortune, in a position to acquit the President the people’s House impeached.