"We can't do it in a massive piece of legislation," Rubio said.
The framework Iranian nuclear deal also shared in the spotlight.
The former governor said it would be "an extreme poverty" if only one Democrat runs.
The Democrat announced he will stay in the Senate.
Former Sen. Jim Webb said he'll be returning to Iowa next week.
"I think the president is in a stronger position," Sen. Ben Cardin said.
"It's outrageous. She should be confirmed," Sen. Ben Cardin said.
McCaskill also said Democrats are not challenging Clinton because of her qualifications.
The former senator joined other female Democrats in praising Clinton.
“Substance and vision does it,” said the New York mayor, who ran her Senate campaign.
“We will have an opportunity to make our entire case in court,” he said.
“We’ve earned the right to be able to try and complete this," he said.
"It exposes a vulnerability that the terrorists, I think, can exploit," McCaul said.
"I cannot tell you the distress in that family at that time," Terry McAuliffe said.
The Ohio governor is visiting South Carolina and New Hampshire this weekend.
“Today, our allies trust us less,” he said. “Our enemies fear us less."
Rep. Jason Chaffetz said last week's gyrocopter incident raised concerns.
“I think there is a lot of discontent from ordinary people," the senator said.
“President Obama’s deal is deteriorating before our eyes,” he said.
“Hillary’s going to be a very formidable candidate,” Huckabee said.
“Reid was effective for his party," Romney said.
Priebus also suggested that Clinton's name recognition could be a weakness.
John Dickerson will take over as "Face the Nation" host in the summer.
"She will defend, I know, her own record for herself," Kerry said.