In November, Americans will make a choice between continued democracy with a vote for Joe Biden, or an autocracy infused with Christian fundamentalist values by voting for Donald Trump. Christian nationalism – the belief that a Christian moral perspective must rule the country’s law and institutions – is a stronger force in this year’s presidential election than ever before. And while much of the focus has been on Trump’s alliance with evangelical Christians, there is another group that could be even more influential – and they might just tip the scale in his favour.

Catholic bishops lead the largest single religious group in the country, with 73 million believers, or a fifth of the population (Protestants as a whole make up a larger group but are divided among various denominations). Their influence is important: Catholics vote at a higher rate than most Americans, and since 1952, their votes have usually gone to the winner. Today, Catholic groups are increasingly working in alliance with evangelical groups, to push through laws, make political change, and throw their support behind the Republican party.

One recent example of this alliance was the scrapping of federal protection for abortion in 2022. US bishops celebrated alongside their white evangelical peers when the Supreme Court overturned the 1972 Roe vs Wade ruling. It was the culmination of a decades-long battle waged by both groups, with the election of Trump proving pivotal. Trump had impressed conservative religious voters when he promised to name anti-abortion judges to the Court – and he delivered. On a 2020 phone call with Cardinal Timothy Dolan of New York, who gushed his support, Trump called himself the “best [president] in the history of the Catholic Church”.

Three of the Supreme Court justices who overturned Roe vs Wade were appointed by Trump, bringing the total of judges raised Catholic to seven out of nine. Trump’s principal adviser on the nominations, his “court whisperer”, was Leonard Leo, a daily Mass-goer who controls a network of ultra-right NGOs. Leo has strong links with the US Conference of Catholic Bishops (USCCB), one of the most powerful lobbying groups in the US.

The USCCB’s obsession with abortion is one of several ways it defies Pope Francis, the Argentine elected in 2013 who has become known for his outreach to the poor and migrants and to people of other faiths, for reforming antiquated Vatican structures, and for deep concern with global warming and the environment. US bishops continue to list abortion as the “pre-eminent” concern when considering candidates for public office, while Pope Francis says one pro-life issue should not take precedence over others – including capital punishment, euthanasia, care for the poor and for all of God’s “creation”.

Francis also argues against politicising faith, urging bishops to be “shepherds” by exercising “closeness, compassion and tenderness”. Yet only a dramatic last-minute intervention from the Vatican prevented the US prelates from forbidding Holy Communion to Joe Biden when he became president in 2021. Biden is a lifelong Catholic, only the second Catholic president in US history, but his defence of pro-abortion law was given as a justification for withholding the sacrament.

There is plenty of diversity and divergence within the Catholic community in the US. But it’s striking that many of the wealthiest lay Catholics support the agenda of the most conservative bishops. Take as an example Thomas Monaghan, founder of the Domino’s Pizza chain, who told a biographer: “I try to remember that my main job is to become a saint.” To that end Monaghan created Legatus, an influential association of wealthy Catholic corporate CEOs, in 1987. It has been described by Catholic TV network Eternal Word as “a sort of spiritual home-base for those Catholics who stand at the helm of America’s entrepreneurial ship”.

Besides Legatus, Monaghan also created – there is no other way to describe it – an entire Catholic-inspired Florida town, named Ave Maria, with a law school at its heart for grooming the next generation of right-wing lawyers. Its curriculum was partly designed by the late ultraconservative Supreme Court Justice Antonin Scalia, and its dedicatory address delivered by Supreme Court Justice Clarence Thomas.

The pizza king also founded Thomas More Law Center (TMLC), one of several Christian advocacy law firms that “reside at the crossroads of church and state,” as another such firm described itself. “Confronting the threat of radical Islam” is one of TMLC’s declared interests. Cardinal Raymond Burke, a leader among right-wing US bishops and a TMLC endorser, has said that standing against Muslim immigration is “the responsible exercise of one’s patriotism”. This aligns with the policies of Trump, who declared a “Muslim ban” against immigrants from certain countries in one of his first acts as president. The ban was overturned under Biden, but Trump says he wants to bring it back “bigger” if he wins a second presidential term.