House Democrats announced this week that they would bring two articles of impeachment against Donald Trump, making him only the fourth president in US history to face such charges. Democratic leaders characterized the occasion as solemn, somber and sad. Republicans, on the other hand, dismissed the impeachment inquiry as a circus and a sham despite the fact that they are themselves the ones trying to reduce it to carnivalesque farce. Even a motion to take a 15-minute bathroom break during this week’s judiciary committee hearings provoked hysterical Republican objections.

The Republican strategy, clearly, is to undermine and delegitimize the impeachment inquiry. Republicans are portraying the inquiry as a hoax and an attempted coup by Democrats desperate to reverse the results of the 2016 election, unrelated to any actual presidential wrongdoing. The White House’s refusal to cooperate with Congress by sending legal representation to the impeachment hearings was explained by Trump counselor Kellyanne Conway as resistance to “colluding with an illegitimate process”.

Related: Nancy Pelosi is bungling the impeachment inquiry into Trump | Moira Donegan

Why are Republicans taking this approach? Largely because they have no other choice, given the considerable weight of evidence that the president did in fact abuse his power and obstruct Congress, as charged in the impeachment articles.

The poet Carl Sandburg is credited with saying: “If the facts are against you, argue the law. If the law is against you, argue the facts. If the law and the facts are against you, pound the table and yell like hell.” Republican yelling and table-pounding appear to be having the desired result, as most polls find that public support for impeachment has leveled off since October. Intense partisan tribalism and the influence of rightwing media outlets such as Fox News mean that few Republicans or even independents will probably change their minds about impeachment no matter what evidence comes out of further hearings.

In the short term, then, the Republican strategy of stonewalling and counter-accusations may pay off. The votes on impeachment in the House and removal in the Senate will almost certainly break along uniform party lines, making it easier for Republicans to portray the process as driven entirely by partisanship. Republican voters outraged by impeachment may be more motivated to vote in 2020, while some independents may be so turned off by the whole spectacle that they either vote for Trump or don’t vote at all.

In the longer term, however, the Republican approach to impeachment will probably prove counterproductive. The party’s critical weakness, as revealed by the 2018 midterm elections, is that it has lost the support of the college-educated and mostly suburban voters (especially women) who once used to reliably vote Republican. By attempting to sabotage the impeachment process and refusing to address the substance of Trump’s actions, the Republican party will further damage its image with these voters and make it even harder to regain a governing majority.

There are many explanations for why college-educated suburban voters have turned against the Republican party; under Trump’s leadership, for example, the party has increasingly become the vehicle of white working-class resentments. But my interactions with college-educated suburban voters, in the course of trying to figure out why they have abandoned the Republican party, have led me to believe that they tend to care about facts and rational argument, to view our country’s top civil servants as serious professionals rather than nefarious agents of the deep state, and to prefer that Congress solve problems rather than devolve further into chaos and dysfunction. They are more likely to be alarmed than persuaded when Trump and other Republican officials serve as conduits for Russian propaganda by spouting baseless conspiracy theories alleging that Ukraine rather than Russia interfered in the 2016 US elections. And they worry about Trump’s trampling of democratic norms and constitutional boundaries on executive power.

The party’s critical weakness ... is that it has lost the support of the college-educated and mostly suburban voters

For all these reasons, Republicans in Congress, by turning the impeachment crisis into a circus, are likely to further alienate the swing voters who cost the party control of the House in 2018 (and may deprive it of Senate control in 2020). When those of us who want the Republican party to appeal to a wider demographic called for it to become a “big tent” party, this wasn’t what we had in mind.

A glimmer of what could have been a better Republican approach to the impeachment inquiry appeared recently in the judiciary committee testimony of the George Washington University law professor Jonathan Turley, who was the sole legal expert called by Republicans. Turley (who did not vote for Trump) conceded that Trump’s phone call to the Ukrainian president “was anything but perfect” but argued that the Democrats were pursuing impeachment too quickly and with insufficient evidence compared with the proceedings against presidents Nixon and Clinton. Turley’s claim that Trump’s actions did not amount to impeachable crimes is highly debatable, but his testimony was notable precisely because he was the sole speaker on the Republican side calling for reasoned debate.

Recently, the Republican congressman Francis Rooney of Florida demanded that several members of Trump’s administration with direct knowledge of the president’s orders on Ukraine – including the secretary of state, Mike Pompeo; the acting White House chief of staff, Mick Mulvaney; and Trump’s attorney, Rudy Giuliani – testify in the impeachment hearings.

“Firsthand accounts like these,” Rooney said, “would affirm that the impeachment process is seeking substantive outcomes based on real facts and accurate information, rather than reflecting a more political objective.”

Democrats will probably dismiss this as more unnecessary foot-dragging, but even the Democratic-leaning Washington Post has editorialized that a lengthier process “may be justified if it results in testimony from administration witnesses. This also might convince more Americans that the impeachment process has been conducted thoroughly.”

But Rooney (who will retire at the end of this term) is an isolated voice on the Republican side, and already he has faced furious criticism from Trumpian loyalists for declining to state whether he is for or against impeachment until he has seen more evidence.

Republicans appear locked into their strategy of trying to dismiss impeachment as a partisan sham, despite the likelihood that this will make it harder to win back college-educated suburban swing voters. In hindsight, Republicans may come to feel that this play for short-term political advantage came at too high a cost.

• Geoffrey Kabaservice is the director of political studies at the Niskanen Center in Washington DC as well as the author of Rule and Ruin: The Downfall of Moderation and the Destruction of the Republican Party