Ted Cruz continues to mop up the evangelical vote, having received an endorsement from James Dobson, founder of Focus on the Family.

The influential evangelical leader announced his support yesterday and the endorsement is likely to help Cruz's recent surge in the polls as he targets the religious vote.

"Ted Cruz's record on religious liberty, life, and marriage is second to none in this Republican field," Dobson said in a statement.

"I have met with the senator on multiple occasions: he is brilliant, articulate, and informed.

"Shirley [his wife] and I have been praying for a leader such as this, and we are confident that Ted Cruz has the moral and spiritual foundations to lead our nation with excellence.

"Speaking as private individuals, we urge conservatives and people of faith to join us in supporting his race for the presidency."

Cruz has spent much of his campaign courting the evangelical vote, holding religious freedom rallies and meeting with national and local leaders.

Despite recent endorsements from a number of religious leaders in the vital state of Iowa, however, Cruz still trails Donald Trump in the polls.

He thanked Dobson who he described as a "voice of hope and a guide to many."

"Dr Dobson has mentored and encouraged three generations of American families," said Cruz.

"Dr Dobson's wisdom and common sense have inspired health and healing in millions of lives. He has rallied people around the world with a vision for happy marriages and beautiful home life.

"I am deeply grateful for Dr Dobson's gift to the world – he has been a voice of hope and a guide to many of us, and I am thrilled to have his support."