Evangelicals are set to play a deciding role for Republicans in the Super Tuesday states, according to Pew research.

Next Tuesday sees presidential primary votes taken in 12 US states and one territory. 

Statistics from Pew's 2014 Religious Landscape Study reveal evangelical Protestant churches make up "huge shares" of Republicans in most Super Tuesday states.

This includes majorities in Tennessee (67 per cent), Alabama (63 per cent), Arkansas (61 per cent) and Georgia (57 per cent).

In Texas, which is the most significant goal of the day with 155 GOP delegates at stake, evangelicals make up 46 per cent of Republicans.

Massachusetts, one of five Super Tuesday states outside of the south, bucks the trend with only 10 per cent of Republicans being evangelical.

With two-thirds of Republican voters across the 12 states saying religion is very important to them, it will be deciding factor in whether Marco Rubio or Ted Cruz can dent Donald Trump's significant lead in the polls.

As Pew was quick to point out, "religious groups rarely vote as a fully unified bloc" but bringing the majority on side will be a deciding factor on Tuesday. This was demonstrated in South Carolina as Trump claimed 34 per cent of white evangelical voters, leaving Ted Cruz with 26 per cent and Marco Rubio with 21 per cent.

Religion is less influential among Democrat voters and those with no religious affiliation are the largest group in three of the 12 states that will vote on Tuesday.

"This includes Massachusetts (where religious "nones" make up 37 per cent of Democrats), Colorado (38 per cent) and Vermont, where fully half of Democrats are religiously unaffiliated," according to Pew.

However black Protestant churches are crucial for Democrat candidates particularly in Alabama where they make up 39 per cent of voters and Georgia (32 per cent).

And although evangelicals tend to side with Republicans, they are still a significant constituency for Bernie Sanders and Hillary Clinton. They make up 20 per cent of Democrats across Tuesday's 12 states and in Tennessee they are the biggest group at 39 per cent.

So expect both Democrat and Republican candidates to be extolling their religious virtues in the build up to Super Tuesday as it is likely to prove a crucial day in deciding the presidential battle later this year.