Ted Cruz surges 10 points ahead of Donald Trump in new Iowa poll

Mr Cruz leads in the poll with 31 per cent, while Mr Trump received 21 per cent

Republican presidential candidate Ted Cruz (Alex Wong/Getty Images)

After months of Donald Trump being a clear frontrunner among the Republican presidential candidates, a new poll shows rival Ted Cruz has surged 10 points ahead of the business magnate in one of the most critical early-voting states.

The poll by Bloomberg and Des Moines Register, released on Saturday, showed Mr Cruz leading in Iowa with 31 per cent of those likely to attend the Republican caucuses, while Mr Trump received 21 per cent.

The poll represents a massive 21-point jump for Mr Cruz from polls in October and it is understood that no candidate has made such a huge leap in five previous caucus cycles.

Mr Cruz’s Iowa state director, Bryan English, told CNN: “We have more work to do, but we can definitely say the message is working.”

Conducted between December 7 and 10, the poll comes after Mr Trump called for a “complete shutdown of Muslims entering the United States", prompting severe criticism from politicians and public figures around the world.

Ben Carson has dropped to third place in Iowa with 13 per cent of the poll; Marco Rubio has 10 per cent, putting him in fourth place; and Jeb Bush has 6 per cent. The remaining candidates have 3 per cent or less.

Since the poll was published Mr Trump has attacked Des Moines Register, Iowa’s largest newspaper, for being biased against him and referred to a CNN/ORC poll, released on Monday, which found Mr Trump has 33 per cent support in Iowa, followed by Mr Cruz at 20 per cent.

In a tweet on Saturday he wrote: “New CNN Iowa poll – Trump 33, Cruz 20. Everyone else way down! Don’t trust Des Moines Register poll- biased towards Trump!”

Mr Cruz also took to Twitter to react to his front runner status:

The results have reinforced predictions the vote in Iowa will be a race between Mr Trump and Mr Cruz, who has a secure base in the state among Evangelical pastors and congregations.

Mr Cruz has spent little money on advertising in Iowa so far, according to CNN, suggesting his popularity could rise further.

However, Mr Cruz's opponents have only just begun to target him. Mr Trump took aim at Mr Cruz for the first time on Friday, criticising his opposition to ethanol subsidies, CNN reports.

Mr Cruz and Mr Trump will face each other at the next Republican presidential debate on Tuesday in Las Vegas.