As the Presidential race heats up, evangelist Franklin Graham has urged Christians to vote, even if it means they have to decide which is the "least heathen" candidate.

In an interview with CBN News, Graham, president of the Billy Graham Evangelistic Association and Samaritan's Purse, said: "There is a left movement within the evangelical community that are telling people, 'If so-and-so wins or this person wins don't vote.' I'm just saying, I don't care who wins and who's out there, you have to vote."

He continued: "And I'm not going to tell people who to vote for, I'm not going to do that – let God tell you who to vote for.

"You may have to hold your nose, you may have to decide which is the least heathen of the two heathen."

Graham is currently undertaking a 50-State tour of the US with the aim of encouraging Christians to pray, get involved in politics and vote for "candidates who support biblical values".

The Decision America Tour involves prayer rallies in each state, and has drawn crowds of thousands. On Tuesday, around 5,000 turned out to hear Graham speak in Denver.

Ahead of the tour, Graham said: "I want to stand on capitol steps and lead this nation state by state in praying for America.

"We'll be praying for our leaders and praying that God would give us politicians who will stand for biblical values. I want to challenge Christians to get involved in the Democratic Party, the Republican Party, and all others to make a difference; to get engaged at every level and to vote.

"The Bible calls us to be salt and light in this world – it's time we got off the sidelines and got involved in actively working and praying to stop the moral decline of this great nation."

He has denied that he has a political motive, however, and in December announced that he was leaving the Republican Party.

"This 50-state tour is not for the Republican Party," Graham said. "I'm as disappointed in them as I am the Democrats."