By Charles Blow – The New York Times.

On the heels of Hillary Clinton’s strong Democratic debate performance, last week Vice President Joe Biden — whose candidacy would surely have drawn support away from her — dismounted the fence and decided not to run for president himself. And then came the spectacular debacle of the Benghazi committee hearing.

At one point during the hearing, Chairman Trey Gowdy, a Republican, said: “This is not a prosecution.” But it was an attempted persecution. It simply failed.

It was a televised witch trial. But the tribunal had before it a woman who would not confess transgression and who defied the flame.

Instead, she was poised, knowledgeable and unflappable. She turned the tables. The committee was on trial, and found wanting in motives, authorities and class.

I keep being surprised by the astonishing degree to which Clinton’s opponents continue to underestimate her.

She is far from flawless, but she is no slouch or dummy. She is sharp and tough and resilient. She is a rock, and she is not to be trifled with.

The Clintons as a couple, and individually, are battle-hardened. They are not new to this. They are survivors. Even when they lose, they survive. No upstart congressman or woman can do more damage than has already been done and dealt with.

Why can’t these people see that? Oh well…

Even before the hearings began, they had been hobbled.

Several Republicans had suggested what many already assumed: that the committee was established — or strayed from its course — in an effort to hurt Clinton’s political prospects.

Make no mistake: this field has been well plowed. This investigation is looking increasingly like a boondoggle: a spectacular waste of time and money.

As a Democratic congressman, Adam Schiff, put it: “The reality is that after 17 months, we have nothing new to tell the families. We have nothing new to tell the American people. We have discovered nothing that alters the core conclusions of the eight investigations that went on before.”

A CNN/ORC poll released last week found that:

“Seventy-two percent of all Americans say they see the Benghazi committee as mostly using its investigative mission for political gain, just 23 percent think it is conducting an objective investigation. Even Republicans are skeptical on this measure, with 49 percent saying the committee is trying to score political points vs. 47 percent who say it is conducting an objective investigation.”

Last week, four top Senate Democrats even demanded in a letter to the Republican National Committee chairman, Reince Priebus, that it pay for the nearly $5 million price tag of the committee, writing “that the Select Committee has conducted a political inquisition aimed at former Secretary of State Hillary Clinton.” This of course was political theory, and will never happen, but needed to be said.

But the spectacle of the hearing itself was an injury different and apart from the motive. Clinton was more composed and commanding, while her Republican questioners vacillated from condescending to pugnacious.

They embarrassed themselves.

And in Clinton’s corner were the Democratic members of the committee, including ranking member Elijah Cummings, who all day delivered blistering repudiations to the committee itself.

Toward the end of the 11-hour hearing, Cummings said to Clinton:

“You have laid it out. I think — you’ve said — this has not been done perfectly. You wish you could do it another way, and then the statement you made a few minutes ago when you said, you know, I have given more thought to this than all of you combined. So I don’t know what we want from you. Do we want to badger you over and over again until you get tired, until we do get the gotcha moment he’s talking about?”

He continued:

“We’re better than that. We are so much better. We are a better country. And we are better than using taxpayer dollars to try to destroy a campaign. That’s not what America is all about.

As he put it: “I just had to get that off my chest.”

Indeed, when Gowdy was asked in a press conference following the marathon hearing what new information he had gathered, he responded:

“I think some of Jimmy Jordan’s questioning — well, when you say new today, we knew some of that already. We knew about the emails. In terms of her testimony? I don’t know that she testified that much differently today than she has the previous times she’s testified.”

That’s right, much of nothing. What a waste.

But not for Clinton. For her, it was a boon. She won another one. It bolstered her image as a warrior and it helped to shore up her support from waffling voters.

This doesn’t guarantee her the presidency of course, or even the nomination, but Republicans did her a tremendous favor with these hearings. The Benghazi committee became a Clinton campaign benefactor.