Over the weekend, Republican Senator Lamar Alexander of Tennessee said that Donald Trump isn't necessarily in the best position to be president of the United States, and boy did Trump disagree. Now a mild feud has erupted.

"Gee, I hope it doesn't ruin my chance to be his vice presidential pick!" Alexander exclaimed, giggling, after Fox News asked the mild-mannered man for his reaction to Trump's comments that he's "not a very effective senator."

It all started a few days ago, when Alexander told CNN, "There's always someone like Donald Trump who runs who has absolutely no chance of winning. I mean, he's famous for being famous. He may be good in business but he's not going to be president."

Trump fired back Tuesday on Fox and was none too pleased.

"The people of Tennessee are very smart. And they don't like being ripped off by everybody that touches this country," Trump said, before throwing down the gauntlet. "And I have a feeling that maybe he won't be there so long."

Zing!

But Trump has a penchant for speaking off the top of his head. Alexander is the current Republican Conference Chairman, and has been talked about as a replacement to hold the #2 position for Republicans after Sen. Jon Kyl retires next year. He was governor of Tennessee in the 80s, served as chairman of the National Governor's Association, was Education Secretary in the 90s and ran for president himself in 1996 and 2000.

And when it comes to hanging on to his current seat, a recent Vanderbilt poll says nearly two-thirds of the state approves of the job he and fellow Senator Bob Coker are doing.

Trump has his own poll to tout. A new Wall Street Journal/NBC poll says Trump's favorability rating is actually higher than Mitt Romney's and Tim Pawlenty's. The billionaire entrepreneur credits his "outsider status" compared to the many politicians, he said, who "are controlled by lobbyists."

But it's early on in the presidential process and Trump hasn't decided if he'll run, so we'll wait to see what happens. Who knows? Maybe The Lamar will back The Don down the road.

Trish Turner contributed to this report.