Superior Mayor Bruce Hagen said Obama "destroyed the fabric of democracy."
“Sadly, a lot of people seem to be falling for Donald Trump’s appeals," O'Malley added.
“It will radicalize more terrorists," Malala Yousafzai said of Trump's rhetoric.
"He’s doing exactly the wrong thing," Graham said.
“A broken system allowed terrorists to come to our home and slaughter Americans," Palin said.
"This is a moment where real intregity is on the line," said Rep. Keith Ellison (D-Minn.).
“The Daily Show” said Trump attracts followers to a “radical ideology” on social media.
Romney also praised Speaker Paul Ryan (R-Wis.) for rejecting Trump's remarks on Muslims.
The author says Trump is worse than the villain of her "Harry Potter" series.
"We've seen this before ... [and] it doesn't end well."
New York Mayor Bill de Blasio (D) says Donald Trump is a "blowhard."
“The No. 1 job of the president is to protect America," he said.
OPINION: The GOP front-runner responds to public concern by scapegoating a religion.
"We are all children of God," the liberal filmmaker told Trump.
The former boxing champ said every U.S. president has "offended some group of people."
"There is a big difference in this," the Iowa Republican said.
"This cruel and dim-witted thinking is not the stuff presidents are made of," he added.
“The state of Israel respects all religion," Netanyahu said of Trump's recent remarks on Muslims.
Democrat Michael Nutter says Trump's proposal on Muslims is "vile."
Homeland Security Secretary Jeh Johnson urged Americans not to "vilify all Muslims."
"This is not, and we should not let it become, a clash of civilizations," she says.
Huckabee says Obama would rather confront critics at home than radical Islamic terrorists.
“This so-called leader of ISIS – he’s not a mastermind, he’s a punk."
Clinton: “I have been consistent about speaking out about the video."