In recent history, a two-term presidency has usually meant the appearance, often in that president's sixth year in office, of a major scandal. The reasons are as unique as the scandals themselves, but what it comes down to is that it's hard to stay in the White House for eight years without something going terribly wrong, whether from the president's own arrogance or venality, or the simple size and complexity of the executive branch. Put a few thousand of your friends and allies into government, give them power and influence, and after a while somebody somewhere is going to do something awful. So Nixon had Watergate, Reagan had Iran-Contra, Clinton had Lewinsky, and Bush had the selling of the Iraq War (a slightly different case, but worse in most ways).

But Barack Obama will be president for less than eight more months, and he's had only piddling little scandalettes. This continues to drive Republicans absolutely batty.

After all, they know, with every fiber of their beings, that Obama is deeply corrupt. He hates America, he's a racial avenger out to destroy white people, he's the embodiment of everything and everyone they despise. Yet somehow they can barely seem to lay a glove on him. So in their latest bit of acting out, Republicans in the House of Representatives are trying to impeach Josh Koskinen, the commissioner of the Internal Revenue Service. The last time Congress impeached a high administration official other than the president was 140 years ago, but nobody ever accused today's GOP of being bound by history.

These Republicans say that Koskinen gave them misleading testimony about the IRS supposedly targeting Tea Party groups (which happened before Koskinen was at the agency), but this is better understood as an expression of their frustration over the failure of that scandal to take down Barack Obama. After all, when that story broke a few years back it seemed like it would prove everything they believed about this administration. Using the cruel hammer of the tax agency to go after political enemies? That's exactly the kind of thing Obama would do! Much to their chagrin, it didn't turn out the way they wanted — even if they did succeed in slashing the agency's budget, making it harder to enforce the tax laws, which is actually just fine with Republicans.

In the end, here's what the IRS "scandal" amounted to. Charged with enforcing vague laws on where the line is between a charitable organization and a political organization, understaffed and undertrained IRS employees were overwhelmed when, after the 2010 Citizens United decision, they were inundated with applications from Tea Party groups for special tax status as 501(c)(4) "social welfare" organizations. They gave the applications from these groups (and from some progressive groups) special scrutiny to make sure they were following the law. Some of these groups had to wait longer than normal for their applications to be approved (though when an organization is waiting, it's permitted to go about its business as if it had already been approved).

And that's it. There was no nefarious conspiracy, no audits of political enemies, no illegal orders from the White House, no sinister plot to use the IRS' power against anyone. Barack Obama was not so terrified of what the East Flipsburg Tea Party Patriots might do to his re-election chances that he brought the full weight of the federal government down upon them.

And so it has been with every controversy during this administration. The story breaks, and Republicans say to themselves, "Now we've finally got him!" They troop before the cameras and spin out dramatic tales of the criminal plot they've uncovered. And then it turns out to be a giant nothingburger.

That's not to say there have been no scandals in the Obama years. There was Solyndra, in which one of the companies given clean energy grants by the government ended up going bankrupt. There was "Fast and Furious," in which an ATF project (begun under the Bush administration) to track the flow of illegal guns went awry.

And of course, there was Benghazi, in which Republicans were convinced that a tragedy in which four Americans died was not just a tragedy, not just a mistake, but the result of criminal wrongdoing on the administration's part, up to and including Hillary Clinton and Barack Obama.

But just like all the other times, Republicans could never find the malfeasance they were so sure was there, no matter how hard they tried — and boy, did they ever try. Benghazi was investigated by the House Oversight Committee, the Senate Homeland Security Committee, the Senate Intelligence Committee, the House Foreign Affairs Committee, the House Judiciary Committee, the House Armed Services Committee, and the House Intelligence Committee. And now, the House Select Committee on Benghazi, a panel created by Republicans with the all-but-explicit purpose of finding something, anything they could pin on Hillary Clinton, has been operating for two years and has spent nearly $7 million. If you just give us a little more time and money, Republicans say, we'll finally get to the bottom of this.

Meanwhile, their thirst for scandal has gone unquenched. That might be because of Barack Obama's personal integrity, but it also might just be luck. There are people of questionable ethics in both parties, and after two terms, at least a few of them are inevitably going to find their way into government. But the really meaningful scandals are the ones in which the president himself is involved. It was Nixon's voice on those tapes that made Watergate the biggest scandal in history. It was Reagan's approval of the scheme to sell arms to terrorists and then divert the profits to the army of thugs the administration had created in Nicaragua that made Iran-Contra such a consequential affair. And as for the Lewinsky scandal, well let's just say Bill Clinton was intimately involved.

But as far as we know, whether you like Barack Obama or not, his hands are pretty clean. And this is something Republicans in Congress simply cannot accept. So they'll keep trying to pin something on him and those who work for him, up until the day he leaves office. And then they'll switch right over to President Clinton, should she be elected.

In fact, I wouldn't be surprised if in a file on a computer somewhere on Capitol Hill, they've already drafted the articles of impeachment.