What’s with the silence from former Trump heavyweights?

If it’s strength they need, there’s strength in numbers.

I’m referring to former officials who worked for Donald Trump, especially the national security stewards, who have declined to come forward publicly and directly to warn voters that he’s unfit to be president — even though, as insiders know well, that’s how they feel.

Imagine the pre-election power of a news conference in which a phalanx of senior Trump advisers stood shoulder to shoulder to deliver that message, each providing first-hand examples of his derelictions of duty. What could better tip the few undecided voters against Trump than former military leaders, on national TV, giving witness to his disregard for the Constitution, the rule of law and America’s national interests? President George W. Bush, 2012 Republican nominee Mitt Romney and former New Jersey Gov. Chris Christie, among others, should join, too. We know what they think about Trump. It’s time to endorse Kamala Harris.

On Monday, 10 retired military officers, including six former generals and two admirals, released a letter in which they not only condemned Trump but also endorsed Harris as “the best — and only — presidential candidate in this race who is fit to serve as our commander-in-chief.” Trump, they wrote, “is a danger to our national security and our democracy. His own former National Security Advisors, Defense Secretaries, and Chiefs of Staff have said so.”

The Harris campaign is exploiting earlier, unprecedented pans from Trump’s former aides. It trolled Trump pre-debate with a new ad on Fox News, featuring condemnatory clips from Vice President Mike Pence, former national security adviser John Bolton, former Defense Secretary Mark Esper and Chairman of the Joint Chiefs of Staff Mark Milley. At the debate, Harris’ guests included two outspoken Trump veterans, White House communications director Anthony Scaramucci and national security official and Pence aide Olivia Troye. And in the debate, she cracked, “If you want to really know the inside track on who the former president is … just ask people who have worked with him.”

The letter, the ad, Harris’ trolling — all of that is well and good, but we need to hear unambiguously from those White House, Cabinet and military notables who actually saw and conversed with Trump regularly. As I’ve noted before, no president in U.S. history has been so damned by so many once part of the inner circle.

Some, including retired Lt. Gen. H.R. McMaster, a former White House national security adviser, have written critical books but otherwise declined to come right out to say, “Voters, beware!” Others, including Milley and former White House Chief of Staff John F. Kelly, have been sources for damning books and articles but mostly remain mute. Still more, including former director of national intelligence and former Sen. Dan Coats, who privately fretted that Trump was somehow beholden to Russian President Vladimir Putin, have been altogether silent. (And then there are the deplorable party-over-country Trump critics, notably former Atty. Gen. William P. Barr and former United Nations Ambassador Nikki Haley, who say they’ll vote for him nonetheless because he’s the Republican nominee.)

McMaster is among the most frustratingly reticent. Last month, promoting his latest book, “At War with Ourselves: My Tour of Duty in the Trump White House,” McMaster told CBS News that Trump was “nasty,” refused to prep, made contrarian decisions “just to spite” his advisers, was “addicted to adulation” and fomented “an environment of competitive sycophancy.” He said Mattis and Secretary of State Rex Tillerson considered Trump a danger to U.S. interests. McMaster said he didn’t agree, though he did volunteer that Trump “sees in authoritarian leaders,” especially Putin, “the qualities that he wants other people to see in him.” That’s not dangerous?

Trump’s actions in encouraging the Jan. 6 attack on Congress and upsetting the peaceful transition of power were “an abandonment of his responsibilities to the Constitution,” McMaster said. But when asked if Trump is fit to hold the office again, he demurred: “That’s the judgment that the American people have to make.” He wouldn’t say how he would vote, despite allowing that the chaos he chronicled “does foreshadow what we might expect in a second Trump administration.”

McMaster, the author of books dealing with leadership, ought to be mobilizing the SOS news conference. What is stopping him and the rest?

In fairness, the military veterans among them are steeped in a culture of deference to civilian government and the commander in chief. That weighs heavily against any action smacking of politics. Yet they served in civilian roles and saw Trump as most Americans could not. It’s their patriotic duty to speak up.

Another possible reason for their reticence: It’s well-documented that taking on Trump causes him to attack, which in turn provokes threats of violence from his most rabid supporters. Romney, the only Republican senator to twice vote for Trump’s conviction on impeachment, last year revealed that he spends $5,000 a day for security. Most people, including former government VIPs, probably can’t afford that.

There is another disturbing factor. Former Rep. Adam Kinzinger, Never Trump Republican, has talked to some of the “boneless wonders” who remain offstage. “I’m just going to spill the beans,” he said on a recent Bulwark podcast: “A lot of these folks, they’re making money now, OK?” — consulting for private equity firms and defense contractors, for example. If their paymasters fear a vengeful Trump will be president soon, their denunciations of their former boss would make them “a liability.”

But, Kinzinger added, as if addressing the fainthearted: “You saw this stuff and you actually care about the future of the country? I mean, you’ve got to speak out! This is like the most important moment.”

Kinzinger held out hope for 11th hour surprises. So should we all.

Jackie Calmes is an opinion columnist for the Los Angeles Times in Washington, D.C.