Imagine you’re the scion of a family that is part of the twentieth-century American elite. You were born into wealth and privilege, but raised to personify modesty, rectitude, and noblesse oblige. You were a war hero. You graduated Phi Beta Kappa from Yale in only two and a half years.

Your career was one of the most accomplished in American history: representative in Congress; ambassador to the United Nations; chairman of the Republican National Committee, where you were forced to ask your party’s president to resign; envoy to China, where you nurtured the relationship between what are today the world’s two largest economies; director of the CIA, where you gave intelligence briefings to the other party’s nominee; vice president; and president.

Your presidency was largely defined by foreign policy. The Warsaw Pact collapsed while you were in office, and you successfully facilitated the removal of Soviet troops from Eastern Europe and the unification of Germany. You got a major nuclear arms deal with the USSR ratified, and as the USSR collapsed, you helped extract the Baltic republics from Russia. You also led a winning war in the Middle East, notable for the broad international coalition you put together.

You lost reelection, but two terms later your son became president. You developed a warm relationship with the Democrat who defeated you. And you show respect to and receive respect from the current president.

Would you want Donald Trump—whose personality and relationship to wealth and fame are the polar opposites of yours, and whose sense of duty and commitment to American security and power within a framework of international institutions are in doubt—to become president?

The man described, of course, is George H.W. Bush. He is 91, and supposedly retired from politics. But his legacy, and the security of the nation, are at serious risk. The first President Bush has one last duty to perform for his country: endorse Hillary Clinton for president.

Given his life, values, achievements, and commitments—not to mention Trump’s attacks on his two sons—why wouldn’t he?

To be sure, we should not overlook the many acts of political expediency and cravenness that helped get George H.W. Bush to the White House. He went from pro-choice to strongly anti-choice to be on the ticket with Ronald Reagan. His 1988 Lee Atwater–led presidential campaign was scurrilous. He deftly used the wedge issues of rights, regulations, and taxes as proxies for race. His vice president was callow, unaccomplished, and probably unfit for the job. The invasion of Panama was dubious at best. He nominated Clarence Thomas to the Supreme Court.

Furthermore, George H.W. Bush has always been a Republican, and he endorsed every Republican presidential nominee until this year. He may not be capable of endorsing Clinton, because it would mean the abandonment of his Republican Party. Refusing to endorse Trump may be as far as he can go.

But George H.W. Bush wasn’t crazy. He tried on the affectations of cultural populism, but he was and remains a member of the New England-New York elite. Though he referred to his grandchildren as “the little brown ones,” he appears to have embraced having a family blended with Mexican immigrants. He was a serious adult as president, in particular in his conduct of foreign policy. He didn’t have to be pushed to repudiate David Duke.

And unlike Donald Trump, he never suggested we should abrogate international treaties, toss aside our international commitments, and disdain diplomacy and international institutions. He didn’t invite Russian aggression by saying we may not come to the defense of NATO allies. And he never held a press conference in which he asked Russia, sarcastically or otherwise, to conduct espionage against his election opponent.

Bush dedicated his career to maintaining an international order that kept the U.S. in a preeminent position of global power, and that prevented the USSR and Russia from extending its power beyond its contiguous sphere of influence. As president, he oversaw what he hoped would be the creation of a new Europe, with a shrunken Russia unable to intimidate Eastern Europe and unable to keep the West on a constant war footing.

If he can get past naked partisanship, it should be easy to endorse Hillary Clinton—the only nominee in at least a century whose experience and preparation for the presidency rival his when he was a candidate.

What about the rest of the Bush family? Barbara appears to loathe Trump. Jeb has already said he will not vote for Trump. Laura hinted she may have already decided to vote for Hillary. And one of his closest former colleagues, former National Security Advisor Brent Scowcroft, has already endorsed Clinton.

George W. Bush has pledged to support Republican candidates for Senate. But he has openly mused that he may be the last Republican president. George W. Bush may have misread Vladimir Putin, but he didn’t openly play footsie with him. That—plus Trump’s attacks on his brother, and on his own legacy—might be enough to switch sides, especially if it was an endorsement accompanied by an endorsement from his father.

Would a Bush family endorsement be a net gain for Hillary? Without a doubt. It might embolden more Republicans to at least disavow Trump. It would make it even harder for the press to treat Trump like something other than an unstable extremist grossly unfit to be in charge of our nuclear codes, military and prosecutorial power, and state secrets. Like Gaullist-Socialist alliances against Marine LePen’s National Front in France, it would signal that Trump is outside what’s acceptable in a liberal democracy, and that protecting the republic is more important than inter-party rivalries. A Bush family endorsement of Hillary Clinton would convince many mainstream Republicans (especially college-educated Republicans and Republican women) to vote for Clinton—there might even be enough converts that Trump would have no path to victory.

Comedian Dana Carvey famously imitated George H.W. Bush with the line “Wouldn’t be prudent!” Prudence is commonly thought of as caution, but it has an older, richer meaning in ethical and political theory. A prudent man knows not only concepts of right action and conduct, but also has experience, sound judgment, and practical wisdom that he draws from to make the right decision in real-world situations. Prudence, under this definition, is one of the highest virtues. It is time for responsible Republicans to put nation before party, and endorse Hillary Clinton for president.

If you were George H.W. Bush, wouldn’t you conclude that’s the prudent thing to do?