If the first three years of the Trump presidency seemed like a rollercoaster ride, then hold on to your hats: as Ronald Reagan put it when he ran for re-election in 1984: “You ain’t seen nothin’ yet”.

Donald Trump begins his bid for a second term on trial in the Senate following his impeachment by the Democrat-controlled House of Representatives last month. Jewish lawmakers — Adam Schiff, chair of the Intelligence committee, and Jerry Nadler, who heads the Judiciary committee — have been key players since the scandal broke in September.

But a number of others featured heavily in the impeachment saga, and not just Ukranian president Volodymyr Zelensky.

There was Daniel Goldman, the Democrats’ top lawyer and chief interrogator on the Intelligence committee, and the president’s ambassador to the EU, George Sondland, whose dramatic testimony in November confirmed that there was a threat to withhold military aid to Ukraine unless Mr Zelensky opened a probe into Donald Trump’s domestic political opponents.

Then there was Lt Col Alexander Vindman, the National Security Council’s top expert on Ukraine, whose family fled the former Soviet Union when he was three.

He torpedoed Republican arguments that the Democrats had no first-hand witnesses of Mr Trump’s alleged wrongdoing by saying he had heard the president’s infamous July call with Mr Zelensky.

“What I heard was inappropriate and I reported it,” he bluntly stated.

When the action turned to Mr Nadler’s committee, the Democrats deployed three constitutional experts – Noah Feldman of Harvard, Pamela Karlan of Stanford and Michael Gerhardt of the University of North Carolina – as witnesses to bolster their case.

All three are Jewish.

Unsurprisingly, some of the president’s defenders have made none-too-subtle allusions to these Jewish connections.

Few have been as blatant as Florida pastor Rick Wiles, who labelled the impeachment inquiry a “Jew coup”, but the dog-whistles have been sounded loud and clear.

Lt Col Vindman was subjected to a blast of charges of dual loyalty by Mr Trump’s media surrogates, while other high-profile supporters of the president sought to undermine the testimony of career diplomats by suggesting that billionaire philanthropist George Soros controls “a very large part” of the State Department.

Even if, as seems highly likely, Mr Trump is acquitted by the Republican-dominated Senate, this will be the noxious backdrop against which the president will fight for re-election.

Throughout both the 2016 campaign and his time in the White House, there have been multiple instances of Mr Trump’s supporters attacking his “globalist” enemies. It’s not hard to discern who they believe is at the heart of this conspiracy.

The closing ad of the president’s 2016 campaign, for instance, attacked the “global power establishment” and, aside from Hillary Clinton, featured pictures of three Jews: Mr Soros, former Federal Reserve chair Janet Yellen, and the ex-Goldman Sachs chief executive Lloyd Blankfein.

Moreover, the president’s angry supporters are now gunning for moderate Democrats who captured Trump-voting, formerly Republican seats in the 2018 mid-term elections but backed impeachment last month.

Elissa Slotkin and Elaine Luria, two Jewish House members supported an impeachment inquiry are among the targets.

Of her prospects for re-election this November, Ms Slotkin said after voting for impeachment: “Whether I’m elected or not, I have to be able to look at myself in the mirror in the morning.”

But — set against this bleak picture — will be the sight of two Jews among the leading contenders for the Democratic presidential nomination. Not that they are likely to have much nice to say about one another.

Bernie Sanders and Michael Bloomberg offer perhaps the starkest differing visions of how the Democrats can defeat Mr Trump. The Vermont senator used his campaign against Mrs Clinton in 2016 to push the Democrats to the left.

His populist attacks on the “billionaire class” are aimed squarely at rebuilding the Democrats’ once formidable support among white working-class voters with an unashamedly socialist pitch.

Mr Bloomberg — a real-life billionaire, no less — offers a mix of social liberalism and fiscal conservatism that aims to appeal to the once-heavily Republican suburbs.

Will either snatch the nomination?

Before they can slug it out between them, Mr Bloomberg needs to dispatch centrist alternatives such as former Vice President Joe Biden and South Bend mayor Pete Buttigieg.

Mr Sanders meanwhile needs to continue his bid to wrest back the support of left-leaning Democrats from Massachusetts Senator Elizabeth Warren. After a difficult few months, he has pulled ahead of Ms Warren once again.

Although he has risen to fifth in the polls just behind Mr Buttigieg and Mrs Warren, Mr Bloomberg’s task looks the more difficult.

By sitting out the early primaries and marshalling his considerable resources to win a swathe of states on delegate-rich “Super Tuesday” on 3 March, the former New York mayor is attempting a strategy which no presidential candidate has yet pulled off successfully.

Mr Bloomberg insists that Mrs Warren and Mr Sanders are “not well placed” to defeat the president. However, early surveys suggest that, while competitive against Mr Trump, he is no more likely to defeat the president than most of his Democrat rivals.

Whoever the Democrats ultimately pick, it seems certain that the vast majority of American Jews will not opt for the president.

Despite his inept attempts to woo Jews — in April, he referred to Benjamin Netanyahu as “your Prime Minister” when addressing the Republican Jewish Coalition — the “kosher vote” remains firmly Democratic.

Mr Trump’s approval rating among Jews in September was 29 per cent — barely unchanged since he entered office and well below the unimpressive 43 per cent he registers with voters overall.

This suggests that in November, the Democrats can expect to win nearly three quarters of the Jewish vote, as Mrs Clinton did in 2016.

Despite his lack of apparent success, Mr Trump will likely continue his efforts to attract Jewish support.

Jews as a percentage of the adult population are above the national average in only two swing states: Florida, which has produced some nail-bitingly close results, and Pennsylvania, which Mr Trump won by less than a single percentage point in 2016.

But in what many expect to be a tight race, any narrowing of the Democrats’ advantage among Jewish voters could help the president in two states he desperately needs to keep in the Republican column.

Mr Trump will no doubt, therefore, continue to highlight the undoubtedly offensive remarks of pro-BDS congresswomen Rashida Tlaib and Ilhan Omar to portray the Democrats as both anti-Israel and antisemitic.

But for so long as his supporters and surrogates continue to drip poison about “globalists” and George Soros onto the airwaves and social media, few US Jews are likely to be persuaded the president is truly concerned about their welfare.