Republicans have “decided on a new strategy” to address a whistleblower complaint against Donald Trump, joked Michael Steele, a former chairman of the Republican National Committee and a frequent critic of the president.

Steele tweeted a slapstick video of a woman trying to sweep sand into the ocean as the tide rolled in.

He was lampooning something noted by veterans of the last impeachment fight, targeting Bill Clinton, and others. One week after the Democrats opened their official inquiry, the president and his party are still improvising a defense and have yet to hit on a coherent response.

“It’s as if the Trump campaign has read the Clinton playbook and at every turn opted for the opposite,” said David Frum, a conservative columnist in the 1990s who was later a speechwriter for George W Bush, writing in the Atlantic.

Where Clinton tried to appeal to voters in the middle and stay focused on policy, counting on impeachment to blow over, Frum wrote, Trump is “wholly obsessed with impeachment … raving nonstop against the whistleblower, the House, and all his political foes – seen and unseen.”

It’s as if the Trump campaign has read the Clinton playbook and at every turn opted for the opposite David Frum

In the week since the House speaker, Nancy Pelosi, announced impeachment proceedings, Trump has vowed to unveil the whistleblower, in defiance of federal protections; accused a Democratic committee chair of treason; quoted a prediction that impeachment would touch off civil war; elevated a false story about a supposed change to whistleblower laws; and generally asked people to believe him instead of their own eyes.

“Almost everything [the whistleblower] has said about my ‘perfect’ call with the Ukrainian president is wrong,” Trump tweeted on Tuesday.

In fact, the whistleblower’s description of the call, which you can read here, matches a summary of the call released by the White House, which you can read here, and those accounts both match Trump’s own summary of his communications with Ukraine.

If there is a point on which Trump and Republicans contend that the whistleblower complaint is wrong on the facts, they have yet to identify it.

“The only defenses we’ve heard from Trump on the Ukraine call so far are false assertions that the whistleblower had no first-hand knowledge and that the [whistleblower] form changed,” tweeted the former federal prosecutor Renato Mariotti.

“That’s because the transcript, on its face, establishes the offense and there’s no good excuse for it.”

Defenses of the president floated by Republicans have been no less scattered than those floated by Trump himself. After a disastrous 60 Minutes appearance in which he exposed his ignorance of the White House call summary, the House minority leader, Kevin McCarthy, unveiled a wan numbered list of “the most important facts we have”.

Among them: “The president did nothing that would be impeachable.”

The minority whip, Steve Scalise, took a different tack, arguing that the impeachment inquiry was “based on false rumors [and] leftwing rage” stoked by “radicals [and] socialists” who “have taken over the Democrat [sic] Party”.

But that line of messaging – that, in short, the Democrats have lost their minds – was undercut by other Republican voices who acknowledged the validity of the whistleblower complaint.

Chuck Grassley, the longest-serving Republican in the Senate, released a statement on Tuesday defending the whistleblower.

“This person appears to have followed the whistleblower protection laws and ought to be heard out and protected,” the Iowan said. “No one should be making judgments or pronouncements without hearing from the whistleblower first and carefully following up on the facts.”

The success of Trump’s messaging strategy does not depend on coherence or convincing the pundits. Ultimately the only important audience for him is the voters.

But the early numbers on that front are not encouraging for the administration. In a CNBC poll released on Tuesday morning, Trump’s approval rating had dropped to an all-time low of 37% – although it had not changed in polling averages.

Clinton emerged from impeachment with buoyed poll numbers and his top Republican assailants were swept from office in the next election.

First on the list of those swept aside was Newt Gingrich, who lost the House speakership, having led the charge to impeach Clinton for making false statements to investigators about his relationship with Monica Lewinsky. At the time, it later emerged, Gingrich was conducting an extramarital affair of his own, with a congressional staffer.

Gingrich said on Fox News on Tuesday it was outrageous for Democrats to investigate Trump for allegedly abusing the power of his office and undermining national security and election integrity by soliciting a foreign country for help in the upcoming election.

“This is, in constitutional terms, a coup d’etat,” Gingrich said. “It is an effort by one branch of the government to destroy the incumbent president of the United States without any regard for the facts.”