The House impeached President Donald Trump on a straight party-line vote. Not one Republican signed on to the most partisan impeachment in U.S. history.

Yet, as we head for trial in the Senate, Democrats seem to be having nervous second thoughts over what they have done.

Minority Leader Chuck Schumer called for the Senate to subpoena four new witnesses the House never heard. Nancy Pelosi signaled Wednesday night that she might not send over to the Senate the articles of impeachment the House had just approved.

Majority Leader Mitch McConnell took to the floor both Wednesday night and Thursday morning. To have the Senate, which is judge and jury of the impeachment charges, to start calling witnesses whom House prosecutors failed to pursue "could set a nightmarish precedent."

Said McConnell, Schumer "would apparently like our chamber to do House Democrats' homework for them."

Schumer's plea for new witnesses is an admission that the House's case for impeaching Trump is inadequate and deficient and could prove wholly noncredible to the American people. After all, if you need more witnesses, you probably do not have the smoking gun.