Despite some Democratic calls for imminent impeachment against President Donald Trump, many responsible party leaders are applying brakes to that notion, starting with would-be House Speaker Nancy Pelosi.

Mr. Trump has already warned that if the Democrats attempt to use their newly won House majority to launch investigations against him, he will strike back in kind. Ms. Pelosi says, however, that her party will focus on demonstrating its ability and willingness to govern responsibly.

This intended disposition to turn the other cheek, rather than use the party’s newly acquired subpoena powers to get anti-Trump incriminating information, attempts to seek the high moral ground. It has the potential of earning more public support beyond the partisan divide from Republicans and independents also fed up with Trump extremism.

The Democrats already have evidence from the midterm results that their staunch defense of Obamacare, especially its provision for coverage of pre-existing conditions, was a big winner for them.

The same is true regarding the protection of Social Security and Medicare benefits, the pillars of the social safety net that has come to be imperative among lower and middle-income voters. These entitlements have clearly become the key to winning back union members and other working stiffs who may have drifted from the fold during the rise of the Trump constituency.

One area in which both Mr. Trump and Ms. Pelosi have expressed an opportunity for common ground is in rebuilding the country’s infrastructure of roads and bridges, which could offer a bounty of jobs around the country. But Mr. Trump as usual talks only in broad generalities.

As for setting aside or tamping down speculation of possible action on impeachment, much obviously will depend on the outcome of the Mueller investigation into Russia’s elections meddling, and now broadening inquiries into Mr. Trump’s business affairs.

His firing of Attorney General Jeff Sessions was long expected. But the sudden, blatant appointment as acting attorney general of Mr. Sessions’ chief of staff, Matthew Whitaker, an open critic of the Mueller inquiry, already has run into resistance on Capitol Hill. Mr. Whitaker has written that looking into Mr. Trump’s business affairs would cross “a red line” beyond the Mueller mandate, but Mr. Mueller’s defenders strenuously argue otherwise.

There is much speculation now, though no certainty, that Mr. Mueller is finally approaching the writing and release of his findings, if not to the public at least to Congress. With at least 30 more House Democrats taking their seats on Jan. 6, their party will hold a clear majority and be in position to subpoena Mr. Mueller and/or his report. By then, it should be clearer what action is required, whether to start an impeachment process in the House, some other legal action or none at all.

Meanwhile, Nancy Pelosi, the Democrats’ most experienced legislative leader, seeking a second stint as House speaker, is being challenged by some new House Democrats, but remains her party’s most formidable figure.

Asked on CBS News’ “Face the Nation” Sunday how she would proceed in questioning the Republicans, Ms. Pelosi said: “Well, we are responsible. We are not scattershot. We are not doing any investigation for a political purpose, but to seek the truth. So, I think that a word you could describe about how Democrats will go forward in this regard is we will be very strategic.”

That response seemed to suggest there would be no random fishing expedition for new impeachment grounds, but rather the examination of existing Mueller or other FBI information providing a valid basis for action against Mr. Trump.

After all the months of time-consuming interrogation of witnesses by professional sleuths, there ought to be sufficient material warranting review without more political free-lancing on the Democrats’ part. They would be well advised, in other words, to pick their targets judiciously in the interest of their own credibility.

As for seeking to regain the speakership, Ms. Pelosi said she was doing so to “protect the ACA.” Had Hillary Clinton been elected in 2016, she said, it would have been safe and she could have gone home, quipping of her need to hold on, “Nobody from California ever gets Potomac Fever.”

Jules Witcover is a syndicated columnist and former longtime writer for The Baltimore Sun. His latest book is “The American Vice Presidency: From Irrelevance to Power” (Smithsonian Books). His email is juleswitcover@comcast.net.