Democratic activists have been laying the groundwork for this moment for months – but the fight has also galvanised Republicans

By the time Nancy Pelosi took her place to announce an impeachment investigation into Donald Trump, nearly every Democrat running for president in 2020 and an overwhelming share of her caucus supported the move.

Trump pressed Ukraine leader to investigate Biden, memo reveals Read more

Seemingly the tide had turned.

After months of beating back calls for impeachment, Pelosi, in a brief but forceful speech, set the stage – for only the fourth time in American history – for an inquiry that could reshape the Trump presidency and next year’s election.

It is a decision weighted with political risk and uncertainty. Not just for Donald Trump, but for Democrats as they hurtle toward an impeachment vote in an election year.

“As events move, the right will do everything in its power to protect Trump,” Neera Tanden, the president of the left-leaning thinktank the Center for American Progress, wrote shortly after Pelosi’s announcement. “If you’ve been pushing Dems to fight, I hope you’re prepared for the war that is coming.”

Progressive groups and activists have been laying the groundwork for this moment for months.

“This is what the ‘blue wave’ fought for: accountability for Trump’s crimes,” said Leah Greenberg, the co-executive director of the Indivisible Project. Her organization helped lead a summertime campaign to pressure Democratic lawmakers to back impeachment.

Now she says activists will make good on their promise to protect vulnerable Democrats who could face a backlash for their decision to support impeachment – and to pressure Republicans to act, which is the focus of a new targeted campaign.

“Having to defend a visibly and openly corrupt president who has flagrantly violated his oath of office is going to have an impact on Republicans,” she said.

Jesse Ferguson, a Democratic strategist and former top aide to Hillary Clinton, agreed. Democrats who believe impeachment is futile are “underestimating the pressure” an impeachment vote places on Republicans, he said.

“It’s one thing to do a Fox News interview defending the president,” he said. “It’s very different when you actually have to take an up or down vote on whether to put the president first or to put the country first.”

Few political observers profess to truly know what the fallout might be.

But one thing is certain: an impeachment of Trump would push the country into mostly uncharted waters. In modern history, only two presidents have faced impeachment – Richard Nixon, who resigned before the House voted, and Bill Clinton, who was ultimately acquitted by the Senate. Both presidents were in their second terms at the time. Their impeachment inquiries offer only a crude guide for understanding the political consequences of triggering this constitutional failsafe.

For months, Pelosi had said impeachment should be a bipartisan effort with broad public support. But she has now moved ahead without either, gambling that Trump’s latest acts will sway public opinion – and the legions of Republicans who have been loth to cross him.

Trump, faced with the most serious threat to his presidency yet, has sharpened his rallying cry. “Presidential harassment!” he has claimed repeatedly, even as his efforts to pressure the Ukrainian president to investigate Joe Biden, the 2020 Democratic frontrunner, come into sharper focus.

Play Video 0:51 'There was absolutely no pressure': Trump on Ukraine controversy – video

A memo of his 25 July call with President Volodymyr Zelenskiy released by the White House on Wednesday showed Trump urged the newly elected Ukrainian leader to investigate unsubstantiated corruption allegations related to Biden and his son Hunter.

Trump has denied exerting improper pressure on Zelenskiy and said the release of the call’s contents revealed nothing inappropriate.

In many ways the charges echo the allegations Trump faced over his campaign’s contacts with Russia during the 2016 presidential election. “Russia, if you’re listening,” Trump said during the campaign, asking it to help turn up potential dirt on his political opponent at the time, Hillary Clinton.

But the complex narrative of the Trump-Russia saga at the center of a months-long investigation was a complicated story for Democrats to tell. By contrast, Trump offered a simple defense: “No obstruction. No collusion.”

Even after the release of a report by special counsel Robert Mueller outlining multiple instances in which Trump allegedly sought to obstruct justice, a majority of the US public oppose impeachment and his supporters remain as loyal as ever despite his low approval ratings.

Trump’s campaign immediately fundraised off the impeachment inquiry, and Republicans are targeting vulnerable members who announced their support for impeachment.

“Make no mistake about it: backing impeachment will cost the Democrats their majority in 2020,” Tom Emmer, the chair of the National Republican Congressional Committee, said.

Meanwhile, Trump’s closest allies on Capitol Hill have amplified the president’s calls for an investigation into unsubstantiated allegations of corruption against Biden and his younger son, Hunter Biden.

Yet Trump’s fixation on Biden may help to underscores a central thesis of the former vice-president’s candidacy: that he is the Democrat best positioned to beat Trump, said Kyle Kondik, the managing editor of Sabato’s Crystal Ball at the University of Virginia Center for Politics.

“One of the upshots of this story is that it makes Trump look like he’s afraid of Biden,” Kondik said.

In a statement on Wednesday, Biden called it a “tragedy for this country that our president put personal politics above his sacred oath”.

“Congress must pursue the facts and quickly take prompt action to hold Donald Trump accountable,” he said in a statement, stopping short of directly calling for Trump’s impeachment.

An unrelenting focus on impeachment in Washington could help solidify the contours of the primary race, as lower-tier candidates, already struggling to break through, find it nearly impossible.

That could help candidates like Elizabeth Warren, who is rising in the polls and was one of the earliest candidates to call for Trump’s impeachment. On Wednesday, she called the call transcript a “smoking gun”.

“If this is the version of events the president’s team thinks is most favorable, he is in very deep jeopardy,” she said.

Despite the groundswell of support for impeachment – which now includes a majority of House lawmakers – many Democrats remain unconvinced that it is the best - or right – course of action.

Some have argued that impeachment would cleave the nation at an especially polarized moment – and could possibly inflict long-term harm on the office of the presidency. Still, others have questioned the wisdom of impeaching Trump when the Republican-controlled Senate is highly unlikely to convict him.

William Galston, a former adviser to Bill Clinton, urged Democrats to reconsider impeachment and pursue instead a formal censure of the president.

“Impeachment is a constitutional option, not a constitutional obligation,” he wrote in in the Wall Street Journal. “It is, in the broadest sense, a political act, and therefore is subject to political tests of feasibility and efficacy.

“If inaction is dishonorable and impeachment futile, censure is the only course that makes both moral and political sense.”

But many of the Democratic lawmakers who have come out in favor of impeachment in the recent days argue that Trump’s actions left them no choice – and said the decision was a matter of principle and duty.

“When the history books are written about this tumultuous era,” the Democratic congressman John Lewis told his colleagues, “I want them to show that I was among those in the House of Representatives who stood up to lawlessness and tyranny.”