Rep. Trey Gowdy (R-South Carolina). AP Photo/Evan Vucci At a certain point, you have to realize you can't hit a fastball. House Republicans don't quite get that they are hopeless at oversight hearings.

They keep losing — and now the chairman of the House Oversight Committee has just introduced articles of impeachment against IRS Commissioner John Koskinen.

I'm sympathetic to the GOP motive, given how the Obama IRS has consistently obstructed and misled Congress in the tax-exemption scandal. But impeachment is no ordinary move.

No agency chief or Cabinet officer has been impeached since 1876. And even proponents admit that there is no chance of Koskinen being removed from office because the Senate will never convict.

Instead, says Chairman Jason Chaffetz (R-Utah), the purpose is public education, "to demonstrate to the American people" that "executive branch officials who violate the public trust will be held accountable."

I'm all for demonstrating malfeasance. But the GOP House has given a five-year display of its inability to successfully demonstrate anything.

From Benghazi all the way back to Operation Fast and Furious, its hearings' impact on public perception has been either zero or negative.

In this June 2, 2015, file photo, Internal Revenue Service (IRS) Commissioner John Koskinen testifies on Capitol Hill in Washington. About 1.8 million households that got financial help for health insurance under President Barack Obama’s law have issues with their tax returns that could jeopardize their subsidies next year. AP Photo/Jacquelyn Martin Take the IRS case. The House Oversight Committee, led at the time by Darrell Issa (R-Calif.), blew it, allowing the IRS' Lois Lerner to deliver a statement proclaiming innocence and then claiming Fifth Amendment protection from having to answer any questions.

Committee member Trey Gowdy (R-S.C.) nearly flew out of his seat to point out that she had just forfeited her immunity.

Too late. She got away with it. That failure is what brings us to impeachment today. But impeachment was never intended to be a mulligan.

Or consider the recent Planned Parenthood hearing in which the Republicans had a very strong hand — videotaped discussions of the buying and selling of body parts of dismembered aborted fetuses, a shocking exposition of what actually lies behind such antiseptic terms as "choice" and "women's health."

Yet the head of Planned Parenthood, so initially defensive that in July she apologized for the callous tone of those involved, ran rings around the committee.

Yet as a PR disaster for the GOP, nothing compares to Benghazi, in which the select committee, armed with truly damning evidence against Hillary Clinton, handed her instead a major victory.

Scattered amid those 11 hours of hearings (which in and of themselves lent Clinton an air of heroism and victimhood) was a powerful indictment of the administration for what happened both before the Benghazi attack (600 requests for more protection, all denied) and after, namely, the concocted fable of a demonstration-gone-bad caused by an offensive video.

Hillary Clinton listens to a question as she testifies before the House Select Committee on Benghazi, on Capitol Hill in Washington October 22, 2015. Reuters Yet the outcome of the hearing is the current conventional wisdom that the committee presented nothing new and never laid a glove on her.

How could the Republicans have blown it so badly?

They had in their hands very new information: a just-obtained e-mail from Clinton to daughter Chelsea the night of the incident saying that it was an attack by an al-Qaeda-like group and, even more damning, a conversation the very next day in which Clinton told the Egyptian prime minister, "We know that the attack in Libya had nothing to do with the film. It was a planned attack — not a protest."

Rep. Jim Jordan, R-Ohio, right, asks a question of Democratic presidential candidate and former Secretary of State Hillary Rodham Clinton, during a hearing on Capitol Hill in Washington, Thursday, Oct. 22, 2015, before the House Select Committee on Benghazi. AP Photo/Jacquelyn Martin This evidence was presented at the hearing, but why not at the very beginning with every camera and microphone running, guaranteeing front-page coverage?

To be followed by clip after clip of Clinton, Susan Rice and the president himself blaming the attack on a film and a protest, a fraud that went on for two weeks. That would have changed the entire proceedings.

True, the media played their part in overlooking and ignoring this prima facie evidence of mendacity and political expediency. But why make it so easy for them? Why bury the lede?

Instead of highlighting this stunning new evidence, the committee offered endless questions about the e-mails of Sidney Blumenthal, someone the public has hardly heard about and doesn't care about.

In each of these cases, Republicans had the facts and the argument. And yet in every one, they failed. What makes them think that they will fare any better in the next iteration, the impeachment of a minor official in an expiring administration?

Chaffetz says that the purpose is to rein in the IRS. I'm all for that. You know how you do it? Win the presidency. Appoint honest new IRS leadership. And get your own Justice Department to do a real investigation.

It's a harder road to accountability. But it gets you to where you want to go.