Have Democrats reduced their chances of denying President Trump a second term by continuing to focus on throwing him out before the end of his first? You can make a good case they have.

Democrats have been itching to oust Trump since the days before he took the oath of office. Obama administration law-enforcement and intelligence agencies launched investigations into candidate Trump’s campaign, contrary to the general rule that such agencies should avoid interfering with electoral politics.

Astonishingly, they relied primarily, if not exclusively, on information bought and paid for by the Clinton campaign, in the Steele dossier. Then-FBI Director James Comey briefed the dossier’s most salacious allegation to the incoming president, an act he presumably considered a form of blackmail.

The supposition, breathlessly ­reported almost daily by certain cable news channels, is that candidate Trump was in criminal collusion with Vladimir Putin’s Russia. But the air has fizzled out of this balloon. Special counsel Robert Mueller, after nearly two years, has produced no indictments pointing to such collusion.

The only collusion that has had a political effect is the belief, held by many Democratic voters, that the Russians somehow switched hundreds of thousands of votes through computer hacking or a handful of diabolically clever Facebook ads. Many such people bitterly cling to their belief that Trump’s impeachment and ­removal from office is imminent.

Democratic politicians evidently feel compelled to cater to these ­delusions, even as it becomes ­apparent that the Mueller investigation will soon end without any recommendation or basis for that.

House Intelligence Committee Chairman Adam Schiff promises he will conduct extensive hearings.

Not much more forthcoming was House Judiciary Chairman Jerry ­Nadler on ABC News last weekend. “We do not have the evidence all sorted out and everything to do — to do an impeachment,” he said. “Before you impeach somebody, you have to persuade the American public that it ought to happen. You have to persuade enough of the — of the opposition-party voters, Trump voters, that you’re not just trying to . . . steal the last — to reverse the results of the last election.”

Nadler says it’s “very clear” Trump has obstructed justice, but the first sign he points to — Trump’s referring to the Mueller investigation as a “witch hunt” — is unpersuasive. That’s probably not an impeachable offense to many of the 35 percent who told Quinnipiac this month that Congress should start impeachment proceedings now.

Now, it’s 28 months since the last presidential election and only 20 months until the next one. In April 2007, after Democrats had just won congressional majorities, Nadler brushed aside calls to impeach then-President George W. Bush. “The timing is all wrong,” he told The Washington Times. “If this were the first two years of his ­administration I would advocate impeachment. A lot of people at home say impeachment, and I’m sure he committed a lot of impeachable offenses, but think about it practically.”

“At home” for Nadler is upscale parts of Manhattan and Brooklyn, areas thick with the urban white college graduates who, along with blacks and Hispanics, are Democrats’ strongest constituencies. On many issues these days — even on racial issues — they’re the party’s most left-wing bloc, and probably the voters most determined to oust Trump.

Urban white college grads had the highest turnout rates in mayoral elections in New York two years ago and in Chicago this year. Blacks and Hispanics, in contrast to past decades, were less interested.

It was young white college grads and gentrifiers who elected Rep. ­Alexandria Ocasio-Cortez in her Queens/Bronx upset last June. And her Green New Deal proposal, ­including things like moving ­toward eliminating beef and private cars, appeals more to that group than it does to blacks and Hispanics.

Pursuing impeachment looks like one more example of Democrats letting AOC-types set their agenda — and distract them from developing policies that will enthuse ­minorities and appeal to suburbanites whose votes they will need next year.