WASHINGTON, DC - SEPTEMBER 8: Lawmakers gather along with lobbying groups, Rudhdi Karnik from the Sierra Club, for a press conference to discuss a Constitutional Amendment on campaign finance reform overturning Citizens United, on Capitol Hill in Washington, DC Monday, September 8, 2014. (Photo by Melina Mara/The Washington Post) (Melina Mara/The Washington Post)

Since Barry Goldwater, in accepting the Republicans’ 1964 presidential nomination, said, “Extremism in the defense of liberty is no vice,” Democrats have been decrying Republican “extremism.” Actually, although there is abundant foolishness and unseemliness in U.S. politics, real extremism — measures or movements that menace the Constitution’s architecture of ordered liberty — is rare. This week, however, extremism stained the Senate.

Forty-eight members of the Democratic caucus attempted to do something never previously done: Amend the Bill of Rights. They tried to radically shrink First Amendment protection of political speech. They evidently think extremism in defense of the political class’s convenience is no vice.

The First Amendment, as the First Congress passed it and the states ratified it more than 200 years ago, says: “Congress shall make no law . . . abridging the freedom of speech.” The 48 senators understand that this is incompatible — by its plain text, and in light of numerous Supreme Court rulings — with their desire to empower Congress and state legislatures to determine the permissible quantity, content and timing of political speech. Including, of course, speech by and about members of Congress and their challengers — as well as people seeking the presidency or state offices.

The 48 senators proposing to give legislators speech-regulating powers describe their amendment in anodyne language, as “relating to contributions and expenditures intended to affect elections.” But what affects elections is speech, and the vast majority of contributions and expenditures are made to disseminate speech. The Democrats’ amendment says: “Congress and the states may regulate and set reasonable limits on the raising and spending of money by candidates and others to influence elections,” and may “prohibit” corporations — including nonprofit issue-advocacy corporations (such as the Sierra Club, NARAL Pro-Choice America and thousands of others across the political spectrum) from spending any money “to influence elections,” which is what most of them exist to do.

Because all limits will be set by incumbent legislators, the limits deemed “reasonable” will surely serve incumbents’ interests. The lower the limits, the more valuable will be the myriad (and unregulated) advantages of officeholders.

The point of this “improvement” of James Madison’s First Amendment is to reverse the Supreme Court’s 2010 Citizens United decision. It left in place the ban on corporate contributions to candidates. It said only that Americans do not forfeit their speech rights when they band together to express themselves on political issues through corporations, which they generally do through nonprofit advocacy corporations.

Floyd Abrams, among the First Amendment’s most distinguished defenders, notes that the proposed amendment deals only with political money that funds speech. That it would leave political speech less protected than pornography, political protests at funerals, and Nazi parades. That, by aiming to equalize the political influence of people and groups, it would reverse the 1976 Buckley decision, joined by such champions of free expression as Justices William Brennan, Thurgood Marshall and Potter Stewart. That one reason President Harry Truman vetoed the 1947 Taft-Hartley Act was that he considered its ban on corporations and unions making independent expenditures to affect federal elections a “dangerous intrusion on free speech.” And that no Fortune 100 corporation “appears to have contributed even a cent to any of the 10 highest-grossing super PACs in either the 2010, 2012 or 2014 election cycles.”

There are not the 67 Democratic senators and 290 Democratic representatives necessary to send this amendment to the states for ratification. The mere proposing of it, however, has usefully revealed the senators who are eager to regulate speech about themselves:

Tammy Baldwin (Wis.), Mark Begich (Alaska), Michael Bennet (Colo.), Richard Blumenthal (Conn.), Cory Booker (N.J.), Barbara Boxer (Calif.), Sherrod Brown (Ohio), Maria Cantwell (Wash.), Benjamin Cardin (Md.), Thomas Carper (Del.), Robert Casey (Pa.), Christopher Coons (Del.), Richard Durbin (Ill.), Dianne Feinstein (Calif.), Al Franken (Minn.), Kirsten Gillibrand (N.Y.), Kay Hagan (N.C.), Tom Harkin (Iowa), Martin Heinrich (N.M.), Heidi Heitkamp (N.D.), Mazie Hirono (Hawaii), Tim Johnson (S.D.), Angus King (Maine), Amy Klobuchar (Minn.), Carl Levin (Mich.), Joe Manchin (W.Va.), Edward Markey (Mass.), Claire McCaskill (Mo.), Robert Menendez (N.J.), Jeff Merkley (Ore.), Barbara Mikulski (Md.), Christopher Murphy (Conn.), Patty Murray (Wash.), Bill Nelson (Fla.), Jack Reed (R.I.), Harry Reid (Nev.), John Rockefeller (W.Va.), Bernard Sanders (Vt.), Brian Schatz (Hawaii), Charles Schumer (N.Y.), Jeanne Shaheen (N.H.), Debbie Stabenow (Mich.), Jon Tester (Mont.), Mark Udall (Colo.), John Walsh (Mont.), Elizabeth Warren (Mass.), Sheldon Whitehouse (R.I.), Ron Wyden (Ore.).

The italicized names are of senators on the ballot this November. But all 48 Senate co-sponsors are American rarities — real extremists.

Read more from George F. Will’s archive or follow him on Facebook.