NBC's TODAY: Mitt Romney said the current Republican presidential campaign has sunk to "a new low" led by the name-calling Donald Trump and pledged in an exclusive TODAY interview to do whatever he could within "political bounds" to stop the current front-runner from becoming the GOP nominee.



"I've wanted to be involved in the campaign, if you will, as a bit of a referee. When there were some foul balls, be able to call them and see if I can't keep people guided on the path to becoming our next president. But the time came when Donald Trump's outrage had reached such a level that I simply had to speak out. You get to the point where you say, your grandkids are going to say to you, 'papa, what did you do to stop Donald Trump?' I had to finally get out and speak," Romney explained.



Asked to explain why he accepted Donald Trump's endorsement in 2012 but is bashing him now, Romney said, "I was seeking his endorsement, now he's seeking now."



"I'm going to do everything within the normal political bounds to make sure we don't nominate Donald Trump. I think he'd be terribly unfit for office. He doesn't have the temperament to be president," Romney said.



"You're calling for nothing less than a suppress Donald Trump movement that will lead to Cleveland at the convention," Lauer said to Romney.



Romney, and being pressed several times, said he's not running for president and doesn't see any scenario he would. However, Romney would not give a Shermanesque statement to Lauer.



Romney said he likes Kasich but he doesn't attack. Romney said if you want to be the nominee you have to prosecute the opposition.