Remember the "impoundment" controversy during the Nixon Administration?

It has been in the news for a while that Trump is diverting funds from the Pentagon and emergency services to pay for his border wall.

I haven't seen it meantioned in connection with this - although I assume some media outlets probably have - a major issue that the Democrats used against Richard Nixon when he was President was his "impoundment" (sequestration) of funds that had been appropriated by Congress. In that case, it wasn't a matter of also diverting the funds to other purposes, but rather not spending them on programs Nixon didn't like even though they had been appropriated by Congress.

Historian Henry Steele Commager wrote (The Defeat of America 1975):

The Founding Fathers were determined that the hardly won power over the purse should never be frittered away, and they wrote it into the Constitution. Now confronted by Congressional votes overriding his vetoes of appropriation bills, Mr. Nixon has resorted to what he calls "impoundment": that is, he refuses to spend money which Congress has appropriated as the Congress wants it spent. What he presents to us here is a twofold violation of the Constitution: first, a nullification of the constitutional provisions giving to the Congress power to appropriate money, and second, a nullification of the constitutional provisions governing the exercise of the presidential veto and providing the method whereby the Congress can override the veto. If Mr. Nixon can substitute "impoundment" for a veto in the matter of appropriations he can, presumably, do so in any other matter, and he has therefore amended the Constitution itself.

In a contemporary article from the time of Nixon's Presidency, Impoundment: A Look at the Record American Heritage 25:1: Dec 1973, Allan Damon reviewed the historical record on Presidential impoundment. While Executive exercise of discretion was not new with Nixon, as Commager observed, Nixon was using it as a practical line-item veto on programs he opposed, rather than responding to legitimate Constitutional concerns or dealing with genuine national emergencies. Damon wrote:

Faced through his five years in office with budgets of this size, President Nixon has freely impounded funds to an extent unmatched by any of his predecessors. It is estimated that to date he has withheld more than $30 billion (although some of it has since been released). In doing so he has added several new dimensions to impoundment.

Where earlier Presidents saw impoundment as a lesser string in the Presidential bow and used it sparingly, Mr. Nixon has made it an integral part of his fiscal policy and has used it on a regular and systematic basis. Where earlier Presidents generally reserved funds from defense and construction budgets, leaving domestic social programs virtually untouched except in wartime, Mr. Nixon has specifically drawn his reserves from a broad range of social-welfare projects. Where earlier Presidents cut only selected projects or limited their expansion within established larger programs, Mr. Nixon has used impoundment to terminate total programs to which he is opposed.

In fiscal 1970 Nixon made his deepest cuts in the poverty programs of the Department of Health, Education, and Welfare. In fiscal 1971 he reserved some $13 billion, the bulk of which came from welfare, education, and housing programs. In fiscal 1973 he withheld more than $400 million Congress appropriated for the food-stamp program. He impounded $8 billion allocated for water reclamation after the Congress had overridden his veto of the original appropriation.

In January, 1973, he announced that he would not request funds for fiscal 1974 for the Office of Economic Opportunity and that he intended to reserve all unspent funds in the 1973 budget for that program while phasing it out. [my emphasis]

Congress passed the Congressional Budget and Impoundment Act in 1974 to curtail Nixon's abusive practices on impoundment.

That was an instance of Congress using its own power to enforce its view of the Constitution. (Twisting the President's Arm: The Impoundment Control Act as a Tool for Enforcing the Principle of Appropriation Expenditure Yale Law Journal 100:1; 1990)

It's helpful to remember this as a time when Congress, and Democrats in Congress, took their Constitutional duites to restrain a rogue Executive much more seriously than Nancy Pelosi and Chuck Schumer do today.

But today's Democratic squeamishness on such matters didn't begin with Pelosi and Schumer. Peter Rodino was the Congressman that presided over the House Judiciary Committee's impeachment hearings against Nixon. (Melissa Block, Watergate Figure Peter Rodino Dies NPR 05/09/2005) But he said this in a 1989 interview:

Rep. RODINO: Notwithstanding the fact that I was Democrat, notwithstanding the fact that there were many who thought that Rodino wanted to bring down a president as a Democrat, you know, he was our president.

SUSAN STANBERG: Yes.

Rep. RODINO: And this is our system that was being tested. And here was a man who had achieved the highest office that anyone could gift him with, you know. And you're bringing down the presidency of the United States, and it was a sad, sad commentary on our whole history and, of course, on Richard Nixon.

So, Rodino, one of the Democratic leaders in the impeachment fight that forced Richard Nixon to resign, recalled his historic achievement as "a sad, sad commentary on our whole history." But half-apologizing after successfully defending the Constitution is a whole different thing that refusing to fight for it.