Republicans theoretically have a 51-49 majority in the Senate, but in practice, it has been 50-49, since John McCain has left the Senate due to his brain cancer and shows no signs of returning.  This makes it difficult for the Senate to pass legislation, of course, but since the Senate needs 60 votes for most matters, McCain's absence is not critical.

...except for judicial nominees.  Under current rules, only a majority of senators is needed to approve judicial nominees. That's why every senator counts.  With McCain's absence, if one Republican senator defects, and no Democrats support Trump's Supreme Court nominee, that nominee will not be confirmed.

It does not appear likely that McCain will return to the Senate, and yet he has not resigned.  There has been some reporting that perhaps the reason he is not resigning is because he wants his wife Cindy to be appointed by the Republican governor of Arizona to take his place.  If so, that is most unfortunate.

Consider that Susan Collins of Maine has already said she will not vote for a nominee who she suspects will not uphold Roe v. Wade.  Lisa Murkowski of Alaska is another pro-abortion Republican.  Either or both could torpedo a Supreme Court nominee.  But if McCain resigned and were replaced by a reliable GOP senator, a nominee could lose one Republican vote and still be confirmed, with Vice President Pence breaking a 50-50 tie.

The number of Democrats who might cross over is expected to be low.  Only three Democrats – Joe Donnelly of Indiana, Joe Manchin of West Virginia, and Heidi Heitkamp of North Dakota – voted for Neil Gorsuch.  The stakes are much higher this time, and the support of all three cannot be counted on.

Remember when the partial repeal of Obamacare failed by one vote: John McCain's?  Hopefully history won't repeat itself, but if Trump's nominee does fail by one vote, we will all know who is responsible.

Ed Straker is the senior writer at Newsmachete.com.

Image: Gage Skidmore via Flickr.