Donald Trump has named 33 influential and conservative Catholics as new advisers.

They include Joseph Cella, founder of the National Catholic Prayer Breakfast, and Sentator Rick Santorum who has twice run for President himself.

Faith Whittlesey, former ambassador to Switzerland, is also on the list, Philly.com reports.

Polls have shown that Hillary Clinton ranks higher than Trump in support from Catholics, much of this due to Hispanic voters, who favour Clinton over Trump by 77-16 per cent.

The Catholic News Agency comments: "Notably, Cella is a signatory of An Appeal to Our Fellow Catholics, an open letter written by George Weigel and Robert P. George in March during the primaries and signed by more than 30 Catholic intellectual and readers."

One interpretation could be that as latest polls show Clinton's lead over Trump is narrowing, Trump and his team are preparing at a deeper level for the possibility of office.

Having wooed evangelicals, the appointment of the Catholic advisers indicates he is now turning his attention to the Catholic Church in a new and profound way.

As with the conservative evangelical faith community, the significance of the Catholic Church in arguing for the "common good" and influencing the moral and spiritual climate in which a President governs cannot be overstated.

Trump, a one-time supporter of abortion who has changed his mind on this contentious issue, has a lot of ground to make up but religious leaders would prefer to work with a President who is for them, not against them.  

"The choice for Catholics in this presidential election could not be more stark," Whittlesey said in a statement released to Philly.com. "Clinton support a breathtakingly radical cultural agenda and judicial nominees which leave no room for the legal protection of the unborn and the ability of Christians to fully and freely practice their faith that is constitutionally protected by the First Amendment.

"Trump will fight for Catholics in defense of life, and their religious liberty."

Cella has in the past described Trump as "manifestly unfit to be president" in a letter that said he was vulgar, appealed to racial fears and questioned his commitment on "life issues".