This is one of those key moments that happens to an administration. You can feel it, see it, and know that this president and his White House have not only made an immoral and unjust decision related to separating families at the border, but have totally miscalculated the politics of the situation.

Living in a small town in Texas day in and day out with many Trump voters, I can tell there is a serious shift occurring. It might be small, and a bit subtle but it is real. The growing opposition to what this administration is doing at the border is powerful and not going away.

You can see this even in evangelical Christian leaders who, up to now, have enabled the worst and un-Christian instincts of this president, but have now begun to speak out about the immorality of what is happening to families on the border.

They realize that you can’t be “pro-family” and systematically destroy family bonds in the name of border security. Even the Rev. Franklin Graham, who has all along been a hypocritical backer of this president, understands the immorality of this White House policy.

The tactics this White House has used in previous incidents of unpopular policy are not working. Blaming it on “criminal elements” from Mexico is not being accepted by the country. Blaming it on the Dems by saying it was their policy is not only untrue and easily proven a lie, it’s not settling well with voters across America.

And trying to attack the press in ways the administration has used prior to this is only fueling coverage and outrage. First lady Melania Trump is wrong on this one: Americans don’t see this as a “both sides” problem with a “both sides” solution. The fault lies entirely with this administration.

The president would be smart and decent (two things he hasn’t always been good at) to understand this policy is like gangrene on a body, and his best solution would be to amputate the infected leg by ending this policy with a stroke of a presidential pen, fire the officials who pushed and implemented it, and give a public address on why he realized this policy was misguided and is making the change.

If the president doesn’t do this soon, the infection will spread and will become a major part of not only the midterm elections but will be a pall over his entire presidency. Even if they don’t understand the moral imperative of ending this border policy, GOP leaders will begin to figure out these actions will put their party in more peril.

In working in politics for the past 35 years, I have seen moments like this come along, and there are only two paths to go. Sink with the original policy and don’t change anything, and try to blame others, or understand the real “moral majority” in America is rising up in frustration and anger, and end this policy quickly and humanely.

In history, it isn’t often assured that presidential administrations understand the shift going on while they are in the middle of it. And because of that willful ignorance, White Houses and the incumbent party suffers in not only the short term but the long term as well.

My suggestion would be that conservatives, GOP leaders and media personalities who have consistently supported this president try to convince this White House of the wrongfulness of this policy.

If that is unsuccessful, then explain to them that the politics of this is just plain dumb. Continuing to back this president in the midst of this border policy is doing a disservice to our country and to the president they so readily support.

Mr. President, you are a person who has always claimed to have good intuition and a gut sense of the politics of our nation. Well, if that is true, you will end the separation of families today. It is both the right thing to do and the smart political move. You can get a quick sense of this by walking and talking to citizens on every Main Street in America today.

Yes, amputating a limb is a sacrifice, and there will be some short-term pain. But do it for the health of families, the ideals of our country and the body politic.

Matthew Dowd is an ABC News analyst and special correspondent. Opinions expressed in this column do not necessarily reflect the views of ABC News.