“The world is a better place because Saddam Hussein is not there,” Rubio said.
Guests also offered updates on the fatal Amtrak crash near Philadelphia.
The former Defense secretary stopped short of endorsing her candidacy.
Sen. Bob Casey, Jr. said Amtrak shouldn't have to choose between safety equipment and bridges.
“Well, I think as a governor, it’s really ultimately about leadership,” Walker said.
"We will have the votes. We're doing very well," he said.
Sanders said Clinton will outspend him in 2016 campaign, but did not criticize her.
The GOP presidential candidate said "we need transformation in our policies."
Sen. Richard Burr (R-N.C.) said the metadata program "is very effective at keeping Americans safe."
Huckabee said that if elected president he would tighten border security.
“Billionaires should not be able to buy elections,” he said on a Sunday talk show.
“We’re very definitely in a new environment," Jeh Johnson said.
"The United States of America is falling behind dramatically its global peers," the Democrat said.
Paul said he would target NSA activities "towards our enemies."
"Yes, we'll pass it. We'll pass it later this week," the Senate majority leader said.
“ISIS is not just in Iraq and Syria,” Rep. Devin Nunes said.
The top Democrat on the Intelligence Committee said she's "very worried" about ISIS.
“Our budget house is in order,” Muriel Bowser said. “Our ethical house is in order.”
“We have not ruled anything out, nor have we ruled anything in,” an NTSB official said.
"Our intelligence was good. But nonetheless, this was an extraordinary risk," Schiff said.
Guests discussing the terror threat included past and present DHS secretaries and lawmakers.
"I do come to this run with qualifications,” the 2016 GOP hopeful said.
“It’s a force that we really haven’t seen before," the senator said.
“We are not adequately defeating them," Sen. Ron Johnson said.