On the issue of regulating money in politics, though, he has remained as steadfastly focused as when he served his freshman term almost three decades ago. He is “the Senate’s most passionate defender of the First Amendment guarantee of unrestricted political speech,” as McConnell told the Supreme Court in asking for rare permission to promote his position before the justices even though he’s not one of the parties in the case.

McConnell has been given 10 minutes of the hour-long argument — a sign the court is seriously entertaining his view that there should be no limits at all on donations to congressional and presidential candidates or to the party organizations that exist to help get them elected.

Anything close to such a landmark ruling would surely stand as one of the biggest triumphs of the senator’s career, whether he survives for a sixth term or not.

It would also herald the biggest change in the campaign finance system at least since the Citizens United case of three years ago. That landmark case struck down limits on independent campaign spending by corporations and unions. Ending donation limits altogether would remove the last big underpinning of campaign finance limits set in the Buckley v. Valeo decision of 1976.