By Cokie Roberts and Steven V. Roberts

The political world is swirling with nutty talk about the imminent demise of the Trump presidency. The I-word, impeachment, and the W-word, Watergate, thread through virtually every conversation. Folks who wouldn’t know a legal tort from a lemon tart solemnly proclaim the president’s guilt.

Protests called “Impeachment Marches” are planned for early July, and organizer Delia Brown told The New York Times, “This is now the zeitgeist; it’s the demands of people we’re responding to.”

Tom Perriello, a gubernatorial candidate in Virginia, fulminates, “We’re talking about, now, something that makes Watergate look like child’s play.”

J.B. Pritzker, who’s running for governor of Illinois, asserts: “We simply do not have the luxury of time to wait for months or years to determine whether the current president of the United States has committed high crimes and misdemeanors. The House must begin the impeachment process before Donald Trump puts us at risk again.”

Pritzker has it exactly wrong. From the evidence that’s surfaced so far, Trump’s actions have been foolish and flagrant, but not fatal. Taking time to build a case against the president is not a luxury, but a necessity. Just because Trump pollutes our politics with his reckless behavior does not mean his critics should follow the same wayward path.

Prosecutors and lawmakers might eventually conclude that the president’s sins justify impeachment proceedings. But responsible Democrats would make a huge mistake if they allow shrill demands for summary judgment to disrupt a measured and thorough legal process.

Sen. Dick Durbin acknowledges that liberal activists “wanted the president gone on Nov. 10 of last year.” But that pressure must be resisted, the Illinois Democrat told the Times: “I want to make certain that we follow the law, follow the Constitution, do it in an orderly way and not get into a crazed political crusade at this point.”

Five months into Trump’s tenure, even many Republicans fear that he is a deranged demagogue who poses a grave threat to the nation’s well-being. His many attempts to sabotage a probe into Russia’s role in the last election show either that he does not understand the rule of law or that he does not think the law applies to him.

More seriously, the president has shown no capacity to learn and grow in office. If anything, as his mistakes multiply and his critics mobilize, he seems more detached from reality. Trump’s recent whine that he’s subject to “the single greatest witch hunt of a politician in American history” shows a staggering capacity for self-delusion.

But are his actions grounds for impeachment? Do the transgressions of the Trump White House make the sins of the Nixon era look like “child’s play”? The only fair answer is no, at least not yet.

Michael J. Gerhardt, who teaches law at the University of North Carolina, wrote in The Washington Post: “The framers established impeachment as a last resort, a check to be used to deal with presidential misconduct when all other mechanisms have failed.”

Those other mechanisms — investigative journalists, congressional fact-finders, independent prosecutors and judges — are far from failing. And as Gerhardt warns, “The more that impeachment proceedings appear to be rushing to judgment or driven by partisanship, the less credibility they ultimately have.”

Credibility is critical. Even though Trump’s approval ratings have sunk to historic lows — 37 percent in the latest Gallup poll — his core supporters continue to back him strongly. They would strenuously resist any attempt to drive him from office, but their anger would be deeper — and more justified — if the evidence condemning Trump was not completely airtight.

Patience is essential. Special counsel Robert Mueller is just starting his work. If there’s a case to be made that Trump obstructed justice by trying to obliterate “this Russia thing,” Mueller will make it.

It’s also possible that Trump will commit other unpardonable offenses. He’s a 70-year-old man who has shown absolutely no ability to control his emotions or correct his errors. Tony Schwartz, who wrote “The Art of the Deal” with Trump, warns in the Post: “The more he feels at the mercy of forces he cannot control — and he is surely feeling that now — the more resentful, desperate and impulsive he becomes.”

For now, however, the Democrats’ watchword should be “oppose,” not “depose.” Block his budget, a document based on cruel priorities and phony assumptions. Take back control of Congress in next year’s elections. Turn the heat up — way up.

But be fair. Follow the law. No crazed crusades.

Steve and Cokie Roberts can be contacted by email at stevecokie@gmail.com.