Questions about whether Donald Trump is an agent of a foreign power have intensified since the Washington Post reported that the president of the United States has refused to share with even his most senior aides the details of his personal meetings with Russian President Vladimir Putin.

But Trump’s supporters don’t seem to care. The president’s approval rating has hardly budged over the past year despite a seemingly endless series of disclosures about the Russia investigation. The website 538, which publishes a daily approval rating for Trump based on its formula for weighting and adjusting public polls, calculates that Trump’s approval rating on January 15, 2019 was 40.8 percent, compared with 39.3 percent exactly a year ago. Trump’s base dismisses each new revelation about Trump and Russia in the same way. They see the investigation as a McCarthyite witch hunt, a conspiracy by the so-called deep state.

There is a precedent in American history for this weird situation, in which there is evidence that a leader has acted against the interests of the United States, yet a large percentage of the American public doesn’t believe it or simply isn’t interested. Many of the same political dynamics that shaped the treason prosecution of Jefferson Davis, the president of the Confederate States of America, seem to be at work today.

On April 9, 1865, Confederate Gen. Robert E. Lee’s surrender to Union Gen. Ulysses S. Grant at Appomattox Court House effectively ended the Civil War. But there were still plenty of loose ends, and one of them was Davis, who fled Richmond, the Confederate capital, just before it was occupied by Union troops. The Confederate president was finally captured in Georgia in May 1865 and imprisoned in Virginia’s Fort Monroe.

Initially, Davis had little support. He was captured in the wake of President Abraham Lincoln’s assassination, and many in the North were eager for vengeance. His backing had also waned in the broken South, where his abrasive personality, his wretched mismanagement of military operations and the economy, and his unrealistic, dead-ender attitude had diminished his popularity by the close of the war.

But Davis quickly regained sympathy thanks to the bungled handling of his case by President Andrew Johnson’s administration. He was imprisoned for two years, and during that time, Southerners who had scorned him in his last days as Confederate president began to rally to him, and he eventually came to be seen as a martyr to their lost cause. Before long, as Ron Chernow wrote in his 2017 biography of Grant, there were reports that “white militias, with telltale names such as the Jeff Davis Guards, were springing up across Mississippi.” Many northern whites, who increasingly wanted reconciliation with the South, also came to believe that the government’s handling of Davis was too punitive. This changing political climate provided the backdrop for Davis’s treason case.

There was no doubt that Davis had broken with the United States. He had been the leader of a government of 11 states that had seceded from the Union. (The two shadow state governments of Missouri and Kentucky, which hadn’t seceded, were also accepted into the Confederacy.) He had fought a bloody war against the United States.

But was that treason? Southern whites had supported the Confederacy and wanted Davis to be its president. Those Americans wanted slavery to continue, and they wanted white power to be undiminished. Davis gave them what they wanted. In fact, one of the concerns looming in the minds of some in the government in Washington at the time was whether Davis’s prosecution might have the unintended effect of leading the Supreme Court to rule that secession was legal.

With political support for the prosecution waning, Davis’s case came to an anti-climactic conclusion. He was freed from prison after his bail was paid by a wealthy group that included Horace Greeley and Cornelius Vanderbilt. On Christmas Day in 1868, Johnson issued a pardon for treason for Confederates, and the case against Davis was dismissed in February 1869.