Donald Trump has said the United States must respond to the Orlando massacre "with force" and accused the Obama administration of holding back law enforcement.
The presumptive Republican presidential nominee also doubled down on his call for a temporary ban on foreign born Muslims entering the US.
"We need to respond to this attack on America as one, united people - with force, purpose and determination," Mr Trump said in prepared remarks a day after the deadliest attack on US soil since 9/11.
"We cannot afford to talk around issues, we have to address these issues head on."
Mr Trump accused the Obama administration and Hillary Clinton of being in "total denial", and said the US needs to "tell the truth about how radical Islam is coming to our shores".
He called for an overhaul of the nation's immigration system, saying if elected in November he would implement a "mainstream immigration policy that promotes American values".
"Immigration is a privilege and we should not let anyone into this country who doesn't support our communities," he said.
Mr Trump also said he wanted to form a partnership with America's Muslim communities.
"I want every American to succeed, including Muslims," he said.
Mr Trump also accused the Obama administration of imposing restrictions on national intelligence officers that keep them from doing their jobs.
Mr Trump's comments came as his Democratic rival called for a number of changes to gun control legislation in the wake of the Orlando shooting.
Earlier, FBI Director James Comey told reporters that Orlando nightclub gunman Omar Mateen had been interviewed twice by agents since 2012, but the US-born man of Afghan descent was never linked to terrorist activity or plots.
Mr Comey said his agency would review its work, but at this point he did not see anything that agents should have done differently.
"Our work is very challenging," he said. "We are looking for needles in a nationwide haystack, but we're also called upon to figure out which pieces of hay might someday become needles."
