Watching Attorney General Jeff Sessions try to bat away Democrats’ smears and innuendo Tuesday, I had two reactions:

One, he’s been an honorable public servant who deserves better than an inquisition.

Two, President Trump made a mistake in naming him attorney general. It’s an error that helped to set a national disaster in motion.

Indeed, my reactions frame the story of the Trump presidency so far. The opposition is ruthless and without principle, but it couldn’t get as far as it has without the president’s inadvertent help.

Start with the Dems, and their desperate hunt for collusion with Russia, obstruction of justice, or just jaywalking — anything remotely resembling a crime will do. Their fury knows no bounds, with character assassination now routine because they can’t handle the truth about the 2016 election.

No matter what question they ask or what insult they throw, the goal is always the same: overturn Trump’s victory. Absent that, they’ll settle for wasting two years of the nation’s time relitigating the election.

Either way, for them it’s a win-win. They win if Trump’s agenda is stalled, and they win bigger if he gets impeached.

It’s a dirty business, but, unfortunately for the people who want the nation to change course, they’re making progress. Just months after being left for dead as political road kill, Dems have played a bad hand very well.

They still don’t have an agenda of their own that will move the economy forward or protect America from terrorism, but they have managed to muddy the waters so much that Trump’s popularity is sinking.

Some 60 percent of the public now disapproves of the president’s job performance, according to the latest Gallup tracking poll. That’s an all-time high, with only 36 percent approving.

At this rate, the Dems will never have to switch course and get back to governing. They will continue their burn-it-down, blow-it-up strategy as long as it works, as yesterday’s shadow boxing masquerading as a Senate hearing demonstrated.

Those poll numbers will also have a chilling effect on Republicans. An unpopular president is not likely to be successful at rallying the troops for difficult legislation.

Some of the blame has to go to Sessions.

I say that because of the one important fact that did emerge from the Senate hearing — that Sessions knew almost from day one that he would have to recuse himself from any investigation of the campaign because of Justice Department regulations.

That fact alone should have persuaded Sessions to turn down the job, or persuaded Trump to name someone else. Either decision would have changed history.

The opposition is ruthless and without principle, but it couldn’t get as far as it has without the president’s inadvertent help.

Consider that Sessions’ recusal meant that the White House effectively lost control of the Justice Department. Rod Rosenstein, the career prosecutor named as Sessions’ deputy, named Robert Mueller as special counsel after simply notifying Sessions and the White House.

And even the act that led Rosenstein to go the special counsel route — the firing of FBI boss James Comey — was bungled. I believe Comey deserved to be removed, but after Trump and the White House gave conflicting explanations that led to a public outcry, Rosenstein sought to put the Russia probe outside the control of the Justice Department.

The entire Trump presidency, then, now hangs in the balance of an unrestrained independent investigation, instigated by the president’s enemies, all because the president picked an AG who could have no role in the most important decision of the young administration.

Sessions said his recusal was required by regulations because he had been a campaign adviser and a Trump surrogate, and the ethics rules prohibit him from involvement in any investigations of the campaign.

With that knowledge, he and Trump should have re-thought his taking the job. But given Trump’s reported anger at Sessions for the recusal — he didn’t think it was necessary — it seems likely that Trump didn’t know about the rules and that they never discussed the implications of Sessions’ role in the campaign.

The case is a perfect example of how Trump, the ultimate outsider, is bedeviled by the culture of insiders. From leaks of classified information to heads exploding every time he does something the bureaucracy doesn’t like, he is having trouble turning his campaign appeal into government performance.

And now, because of Mueller’s appointment, Trump faces a serious predicament.

A fundraising email sent under Trump’s name captured the frustration. “If you told me this would happen in America, I wouldn’t believe you,” it read. “The losing political party is using a conspiracy theory — without having a single shred of evidence — to DERAIL a constitutionally-elected president.”

It went on to blast Comey, the Obama administration and the “fake news media” as part of an effort “to SABOTAGE us . . . this is a threat to our republic — we can’t let them win.”

There is much truth in the charges, yet truth alone is not nearly enough to win the day. The president needs to find solutions that get the public back on his side, and he needs to find them fast.