The founders were wary of corporate influence on politics — and their rhetoric sometimes got pretty heated. In an 1816 letter, Thomas Jefferson declared his hope to “crush in its birth the aristocracy of our moneyed corporations, which dare already to challenge our government to a trial of strength and bid defiance to the laws of our country.”

This skepticism was enshrined in law in the early 20th century when the nation adopted strict rules banning corporations from contributing to political campaigns. Today that ban is in danger from the Supreme Court, which hears arguments next month in a little-noticed case that could open the floodgates to corporate money in politics.

The court has gone to extraordinary lengths to hear the case. And there are worrying signs that there may well be five votes to rule that the ban on corporate contributions violates the First Amendment.

The origins of the ban lie in the 1896 presidential race, which pitted the Republican William McKinley against William Jennings Bryan, the farm-belt populist. Bryan was a peerless orator, but McKinley had Mark Hanna — the premier political operative of his day — extracting so-called assessments from the nation’s biggest corporations and funneling them into a vast marketing campaign.

McKinley, who outspent Bryan by an estimated 10 to 1, won handily, proving Hanna’s famous dictum: “There are two things that are important in politics. The first is money, and I can’t remember what the second one is.”

Popular outrage over corporate contributions reached a high point in the 1904 election.

The defeated candidate, the Democrat Alton Parker, charged — accurately, it turned out — that his opponent had been bankrolled by large life insurance companies. “The greatest moral question which now confronts us is,” Parker insisted, “shall the trusts and corporations be prevented from contributing money to control or aid in controlling elections?”

In 1907, Congress passed the Tillman Act, the first federal law barring corporate campaign contributions. States adopted similar laws.

Since then, Congress has repeatedly ratified the federal ban. In 1925, it folded the Tillman Act into the Federal Corrupt Practices Act. In 1947, it made clear that the ban included not just corporate contributions, but corporate expenditures on campaigns — and that it also applied to labor unions. In the 2002 McCain-Feingold law, Congress once again underscored that corporations cannot contribute to campaigns.

It is inconceivable that Congress would now try to lift the ban. Americans are far too angry at Wall Street and the obvious failure of government regulations. But the Supreme Court has decided to force the question: It took a case, Citizens United v. Federal Election Commission, in which the ban on corporate contributions was not a central issue; told the parties to prepare legal briefs on the ban’s constitutionality; and rushed to put oral arguments on the calendar in September before the new term even starts.

The court’s conservative majority has been aggressively championing the rights of corporations, but overturning the contributions ban would take it to a new level. Corporations have enormous treasuries, and there are a lot of things they want from government, many of which clash with the public interest.

If the ban is struck down, corporations may soon be writing large checks to the same elected officials whom they are asking to give them bailouts or to remove health-and-safety regulations from their factories or to insert customized loopholes into the tax code.

If the conservative justices strike down the ban, they would be doing many things they disavow. They would be substituting their own views for the will of the people, expressed through Congress. They would be reading rights into the Constitution that are not expressly there, since the Constitution never mentions corporations or their right to speak. And they would be overturning the court’s own precedents.

The only hope is that the court is listening to Americans. As it weighs the constitutional issues, it should be mindful that this is another historical moment in which the public is committed to strengthening the wall between government and big business, not tearing it down.