Democratic candidates have been advised to avoid talking about the potential impeachment of Donald Trump, even though a majority of Americans – and 75 per cent of Democrats – support such a move.

Three weeks from midterm elections that will determine whether Democrats flip the House of Representatives, the lower chamber of Congress where any proceedings against the president would begin, candidates and officials are doing all they can to avoid the I-word.

In a calculation that has upset those pushing for Mr Trump’s impeachment, party officials have calculated that raising the issue could play badly among the independent and moderate Republicans they are seeking to win over. They fear it would also energise Mr Trump’s base.

Speaking in August on the day Mr Trump’s former lawyer, Michael Cohen, pleaded guilty to campaign finance fraud, and there was intense speculation as to what might befall the president, Nancy Pelosi, the Democrats’ leader in the house, insisted impeaching him was “not a priority”.

“If and when the information emerges about that, we’ll see. It’s not a priority on the agenda going forward unless something else comes forward,” she told the Associated Press.

Ms Pelosi’s decision has led to a remarkable degree of message discipline.

From Democrats such as Harley Rouda, contesting California 48th congressional district, to Angie Craig seeking to bag Minnesota’s second, and the president of EMILY’s List, a DC-based group that supports women Democratic candidates nationwide, their carefully calibrated responses are strikingly similar when asked whether they support impeachment – namely that Robert Mueller should be given time to complete his investigation into alleged collusion between the Trump campaign and Russia, that voters do not really bring up the issue, and in the meantime, they are focussed on promoting a “positive agenda” about affordable healthcare and the economy.

Even Justice Democrats, a political action committee that supports progressive policies and backs candidates such as New York’s Alexandria Ocasio-Cortez, says it wants to promote “bold ideas” and that being anti-Trump cannot be its main message, according to Nasim Thompson, a spokeswoman.

The two Democratic congressmen who tabled impeachment legislation against Mr Trump in the house, Al Green and Brad Sherman – both faced stern criticism from their party leadership for doing so – have avoided mentioning the issue on their re-election campaign websites.

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Mr Green, of Texas, who still has a link to the legislation on his main site, failed to respond to questions as to whether he still supported such a measure.

Mr Sherman, who represents California’s 30th congressional district, said in a statement: “I stand by my legal conclusion there is sufficient evidence to conclude that Donald Trump has committed obstruction of justice as defined by Section 1512 B3 and accordingly should be impeached.

“I believe that most of the voters in my district know of my efforts regarding impeachment and accordingly when I speak to them I am focused on other issues although whenever people bring up impeachment, I am happy to talk about it.”

The only Democrat who has made headlines for defending his support for impeaching the president appears to be Beto O’Rourke, who is challenging Texas Republican senator Ted Cruz. Speaking this week, he also said Mr Mueller’s probe should be completed.

Pressed on the issue, he added: “I would liken impeachment to an indictment. There is enough there to proceed with the trial for a full vetting of the facts and to make the best informed decision in the interests of this country and our future.”

Christina Greer, associate professor of political science at New York’s Fordham University, said most Democrats had decided impeachment was not an issue that was polling with voters and they were focussed on other issues.

CNN legal analyst Jeffrey Toobin suggests Trump’s Sessions tweet ‘grounds for impeachment’

Yet the Democrats’ strong reluctance to discuss impeachment comes even though a majority of Americans – 49-46 – have said they support Congress going ahead with such a move. The Washington Post-ABC News poll published at the end of August also suggested 75 per cent of Democrats, 49 per cent of independents and 15 per cent of Republicans, backed it.

The instruction to Democrats not to talk about impeachment appears to have been delivered by Mr Pelosi at the time of Mr Cohen’s guilty plea. Politico said, speaking to Democrats in their home districts, her leadership team advised the politicians to frame the plea as part of a corrupt administration that needed a Democratic check in Congress. They were told to be wary of talking about impeachment as “it could backfire”. The New York Times said Mr Pelosi’s team also dispatched a memo to candidates making the same point.

Some in Washington were doubtful Ms Pelosi would have wished to leave a paper trail. One political strategist, who asked not to be named, said: “As Martin Lomasney – the late, larger-than-life one-time political boss of Boston – would have said ‘Never write if you can speak; never speak if you can nod; never nod if you can wink’.”

A senior official in Ms Pelosi’s office told The Independent they could not confirm whether the 78-year-old from San Francisco had spoken such words to her members in an August conference call.

“There are talking points on our positive message that take place on a daily basis when we are in session. Members do get these talking points and that has allowed us to be incredibly focussed on that positive message,” the official said.

(Getty (Getty)

Asked if Ms Pelosi had told candidates not to discuss impeachment, the official added: “The leader has been asked a lot of times about this and has been clear [impeachment is not her focus]. This is not something we have had to do a lot of convincing people about – they get it.”

Ms Pelosi’s decision to avoid talking about impeaching Mr Trump carries potential danger. If the Democrats fail to win the house, there would be an impassioned post-mortem as to whether the party chose the correct campaign strategy. It is unclear whether Ms Pelosi would survive as the Democrats’ leader after such a defeat.

Several groups are still pushing for Mr Trump’s impeachment. The organisation Impeach Trump Now was set up shortly after his election, and Catherine Ross joined its advisory board before he took office.

Ms Ross, a professor of law at George Washington University Law School, said even at that point, she believed Mr Trump’s apparent breach of the emoluments clause of the constitution, which prohibits members of the government accepting gifts, was sufficient justification for an impeachment investigation. She said that since then further evidence had mounted.

Ms Ross said she sympathised with Ms Pelosi’s tactical dilemma ahead of the midterms, but said congressional officials from both parties had failed to show leadership.

“I can understand her decision. But I would at least wish if she is not out in front, she would give her blessing to other leaders who could be out in front.”

Another organisation pushing for impeachment is Need to Impeach, a campaigning group established by billionaire hedge fund manager and philanthropist Tom Steyer. Mr Steyer has spent $50m (£38m) on television adverts and a Times Square billboard calling for impeachment.

His group’s petition has gathered 6 million signatures and he claims Mr Trump has commuted nine impeachable offences, including obstruction of justice and abusing the pardon power.

Keven Mack, a senior strategist for Need to Impeach, said Democrats typically spent millions of dollars trying to persuade people they were moderate on all issues, then wondered why there was no excitement among their grassroots supporters ahead of elections. He claimed the party was experiencing its lowest level of elected office since the 1930s.