Billionaire businessman and reality television star Donald Trump has moved to the top of the 2016 Republican nomination for the US presidential candidate, according to a new poll.

The new CNN/ORC Poll, released on Sunday, shows Trump at 18% support among Republican voters, with former Florida governor Jeb Bush trailing behind at 15%.

"There is a movement going on. This is more than me," Trump told CNN, adding the poll results were not surprising. "People are tired of these incompetent politicians in Washington that can't get anything done."

The poll shows that Trump's support among Republican voters increased six percentage points since late June, while support for Bush and Wisconsin Governor Scott Walker has not changed considerably. Walker has 10% support among Republicans and Republican-leaning voters.

Trump has surged into the lead in the race for the White House, despite a series of recent controversial statements.

The 69-year-old has sparked a controversy by denouncing the military record of Republican Senator John McCain, who was captured during the Vietnam War. McCain was a prisoner of war in North Vietnam for five and a half year, from October 1967 to March 1973.

Speaking at a conservative forum last week in Iowa, Trump said the 2008 Republican Party presidential nominee was only considered a hero “because he was captured. I like people who weren't captured."

Trump has also come under severe criticism for his inflammatory comments about Mexican immigrants in the US, calling them drug dealers and “rapists.”

During his presidential campaign announcement on June 16, Trump emphasized the need to curtail immigration from the southern border and slammed Mexican immigrants for "bringing crime" to the US.

Trump has come under fire from his fellow Republican candidates and party leaders for making incendiary remarks.

"I don't think Mr. Trump is qualified to be commander-in-chief," Senator Lindsey Graham told ABC News on Sunday.

Last week, former Texas Governor Rick Perry called Trump’s presidential bid "a cancer on conservatism."

On Sunday, Perry elaborated on those comments, saying Trump’s concepts “are out of line with the old historical conservatism."