A national political poll by Monmouth University ranks retired neurosurgeon Dr. Ben Carson in first place.

The survey report notes that it’s difficult to identify a “top tier” in the GOP 2016 presidential candidate field.

The poll shows Republican voters care the most about national security and gun control.

Monmouth University’s poll asked voters to pick who they want to see as the Republican nominee.

The results were reported in the poll:

– Republican and Republican-leaning voters are divided among commentator Dr. Ben Carson (11%), Wisconsin Governor Scott Walker (10%), Bush (9%), Rubio (9%), and former Arkansas Governor Mike Huckabee (8%). – Other preferences include Kentucky Senator Rand Paul (6%), Texas Senator Ted Cruz (5%), New Jersey Governor Chris Christie (4%), former Texas Governor Rick Perry (4%), former Pennsylvania Senator Rick Santorum (3%), businesswoman Carly Fiorina (2%), South Carolina Senator Lindsey Graham (2%), and businessman Donald Trump (2%). – Louisiana Governor Bobby Jindal (1%), Ohio Governor John Kasich (1%), and former New York Governor George Pataki (0%) round out the list.

However, the poll indicated, “None of these candidates scores higher than “undecided,” which clocks in at 20%.”

Dr. Ben Carson and Sen. Marco Rubio (R-FL) were the two GOP candidates who increased the most since Monmoth University’s last poll in April.

“This is very positive news for our campaign. What we are doing is working. It is at times like this that we must step on the gas and build upon our momentum,” said Barry Bennett, Dr. Ben Carson’s campaign manager.

The poll was conducted over the past week and has a plus or minus 5.2 percent margin of error.