CNN

It could be the beginning of the end for Hillary Clinton.

Bill Richardson's endorsement of Barack Obama today is huge. Richardson, after all, served under President Bill Clinton as ambassador to the U.N. and secretary of the Energy Department. He's also a friend of the Clintons who watched the Super Bowl together with the former president last month.

So it couldn't be easy for Hillary Clinton when Richardson – whom both candidates had lobbied hard for an endorsement – came out today and called Obama a "once-in-a-lifetime-leader." Richardson said the speech Obama gave on race "appealed to the best in us."

The New Mexico governor and former presidential candidate's endorsement carries a lot of weight.

To read more and contribute to the Cafferty File discussion click here