This vote was to kill a nonbinding resolution proposed by the Democrats who hoped to pressure President Eisenhower to not use the recess appointment power to fill a vacancy in the Supreme Court. (This vote failed, and the resolution was subsequently passed.)

Although the vote occurred in an election year, there is no indication that this vote was about election year appointments specifically. Eisenhower had used the special recess appointment power to make previous appointments to the Supreme Court, and Democrats objected to further use of the recess appointment power. No President has used the recess appointment power to appoint a justice of the Supreme Court since then.

A recess appointment is made while the Senate is in recess, and while such appointments do not require Senate approval (as all other nominations do) they instead expire at the end of the subsequent legislative session (these days, a calendar year). The Washington Post explained:

Each of President Eisenhower’s SCOTUS appointments had initially been a recess appointment who was later confirmed by the Senate, and the Democrats were apparently concerned that Ike would try to fill any last-minute vacancy that might arise with a recess appointment. Not surprisingly, the Republicans objected, insisting that the Court should have a full complement of Justices at all times.

These days, the Senate often holds pro forma sessions, by gaveling-in for one minute each day, rather than go on recess in a time when the President is expected to use the recess appointment or pocket veto power, thus typically preventing recess appointments. On Feb. 14, 2016, President Obama stated that he would not use the recess appointment power to fill the vacancy caused by the death of Justice Scalia, which occurred during a Senate recess.