In most Presidential election years, the most important vote is the vote for President of the United States. This year, the most important vote looks like the vote for control of the Senate. Regardless of who wins the White House, the freedom that Americans have taken for granted -- taken too much for granted, for far too long -- can be destroyed by whomever the next President puts on the Supreme Court.
Since the Senate has the power to approve or disapprove whatever nominee any President wants to put on the High Court, that makes the Senate this country's last line of defense against any headstrong President who puts his or her own power ahead of the freedom of more than 300 million Americans and of future generations.
The Senate is also the last line of defense against any President who exceeds his or her own authority, and thereby destroys the Constitution's balance of power among the three branches of government that has kept this country free for more than two centuries.
If either party -- whether Democrats or Republicans -- unites behind a President with no regard for the Constitution, that party can change the fundamental nature of American government, leaving not only the incumbent President, but future Presidents as well, able to rule virtually by decree.
When the Democrats controlled both Houses of Congress, as well as the White House, we came dangerously close to that, with President Obama virtually repealing the immigration laws passed by Congress and issuing executive orders on this and other issues that simply took over the legislative power from Congress.
Fortunately, there was still a third branch of government -- the federal judiciary -- which put a stop to some of these illegal actions. But, if that third branch of government is also taken over by one party, there is nothing left as a barrier against unbridled power.
The Democrats are united behind Hillary Clinton in a way that the Republicans are by no means united behind Donald Trump. Mrs. Clinton also has overwhelming support by the media in a way that Mr. Trump never has and never will have.
If either of these headstrong and self-centered individuals were to overstep the Constitutional boundaries as President of the United States, and endanger the freedom of Americans, only Donald Trump faces any real danger of being impeached by the House of Representatives and then being removed from office by the Senate.
This is not to predict that either of them will in fact be impeached by the House and removed by the Senate. But penalties exist in the law not just to punish people, but to deter them from doing things that the penalties are there to prevent.
Trump would be on a shorter leash, even if the Republicans controlled the Senate. And there is no way that he doesn't know that fact, with some Republicans already refusing to endorse his candidacy and some even announcing that they plan to vote for Hillary Clinton.
But, with the Democrats controlling the Senate, Mrs. Clinton would know that she had a blank check, instead of a Constitutional check on her powers. With the Senate and the media on her side, there would be virtually nothing she could not get away with.
Control of the Senate matters hugely, no matter who gets into the White House. It matters for the future of the Supreme Court, on which the rule of law depends, and it matters for keeping any President from running this country like a banana republic.
The politically divided government, which the media so often and so loudly lament, may be all that can keep the next four years from being the last four years for Constitutional government and the freedom that depends on it.
Republican control of the Senate is a necessary, but by no means sufficient, precondition for keeping a headstrong President within bounds. There are still painful memories of the preemptive surrender when Senator Lindsey Graham announced that he was going to vote to confirm Sonia Sotomayor to the Supreme Court, even before she had been examined by the Senate.
Regardless of who wins the White House or the Senate, the voters are going to have to keep their feet to the fire, to make sure that Senators do not simply take the path of least resistance. That path usually leads downhill, sometimes very far downhill.