Presidential elections are on everyone’s minds and TV sets these days because presidents matter. In America’s democracy, presidents are its singular most important leaders. Heightened attention to their selection and performance reflects how critical they are to the nation’s strength and survival.

In February, five living presidents were celebrated—Jimmy Carter, Bill Clinton, George W. Bush, Barack Obama and Donald Trump. It is a remarkable democratic achievement and a testament to America’s confidence that the country transitions power peacefully from administration to administration regardless of political party. Republicans yield to Democrats who yield to Republicans.

Unlike other countries, America’s previous presidents are neither hounded nor capriciously thrown in jail. Instead, our former commanders-in-chief live and travel freely.

Unfortunately, they are also currently being ignored and denigrated. That not only deprives America of potential power, it comes at a cost.

Presidents in the late 20th and early 21st centuries relied on their predecessors for counsel and collaboration. Ex-presidents have been previously used to free hostages in hostile foreign lands, participate in humanitarian endeavors or lobby for difficult bipartisan policies. It had become commonplace to deploy former presidents—regardless of party or personality clashes—to help administrations in power do hard things. This was true for nearly every modern president.

There are, however, two very notable exceptions: Franklin Delano Roosevelt and Donald John Trump.

Once in office, Roosevelt dissed Herbert Hoover at every opportunity. Trump remains allergic to all things Obama, making the African-American 44th president the 21st century’s Herbert Hoover.

Ignoring a young Hoover in the past and vibrant Obama today has deprived the nation of opportunities both for greater domestic harmony and difficult foreign intermediation. America’s once clear, sometimes singular, voice abroad is now processed and overamplified as a noisy global cacophony.

Disrupting the presidential continuum, comity, and collaboration can be blamed for some of today’s international ills. Could Obama, for example, be quietly deployed to make diplomatic overtures today to a sanctioned, struggling and coronavirus-infected Iran? Where could Clinton, Carter or Bush be leveraged?

Trump may admire Andrew Jackson, but he is emulating Roosevelt by trying to stack the courts, open up state coffers and punish his perceived adversaries and enemies. It’s hard to accept, but what FDR successfully did was erase Hoover. He never allowed Hoover’s works be recognized. Hoover was roundly defeated in the 1932 election, persona non grata at the White House and exiled to the farthest end of the continental United States at Stanford University.

Where Hoover had the foresight to build the Hoover Dam, Roosevelt had the pettiness to rename it Boulder Dam. Policy after policy, person after person, if the scent of Hoover lingered on a bill, banker, business, politician or pet project, it was regarded as the pervasive stink of someone who had defecated in the Oval Office.

When Roosevelt died, he left an unprepared Harry Truman to take over as his constitutionally mandated successor. Truman inherited an ongoing war, the overblown legacy of a four-term president and a decision to make about blowing up Japan with the world’s newest weapon—the atomic bomb.

FDR never deeply briefed Truman, and 82 days into his vice presidency, Truman was thrust into the role of 33rd president. He sought a lifeline from the only other person alive who knew the pressures he was facing and understood the presidency. He needed an ex-president, and the only one available was a vilified California Republican: Herbert Hoover. Truman and Hoover joked that this was the beginning of a “former presidents’ club.”

Hoover, desperately seeking rehabilitation and respect, hungrily accepted the role of hidden adviser, careful consultant, proven European post-war logistics master and savior.

Trump has not only taken a page from FDR’s playbook, he’s writing a whole new chapter on political purges, with updated sections on baiting, backbiting and bullying former presidents. Barack Obama, meet Herbert Hoover.

In the recent past and on solemn national occasions, group photos of living presidents showed the world America’s power and unity. It is remarkable to see pictures of Nixon, Ford, Carter, Bush and Clinton together. It is powerful to know that they relied on each other for insights into foreign leaders, difficult hostage negotiations, secret two-track discussions with adversaries, joint humanitarian missions and general counsel on thorny issues.

Today, those photos seem like relics of a bygone era. Instead of former U.S. presidents posing for Associated Press photos in the Oval Office, spying foreign journalists are now welcomed into the White House to shoot Russian Foreign Minister Sergei Lavrov and Ambassador Sergey Kislyak who yuk it up near Andrew Jackson’s portrait.

American presidents past and present are a national asset and should be welcomed into the White House—whether ushered in the front door or snuck in the back. Unfortunately, the only president with an open invitation today is Vladimir Putin.