Former GOP candidate Newt Gingrich said it would be "highly implausible" for him to join Mitt Romney on the ticket as vice president.

Asked about his interest in serving as Romney's number two, Gingrich refused to rule it out, but made clear that he was not expecting to be in the running.

"I think that's highly implausible," he said on NBC's "Meet the Press." "I find that as implausible as you find it."[...]

Appearing alongside Maryland Gov. Martin O'Malley, who has been rumored to be a 2016 Democratic candidate for the White House, Gingrich offered pointed advice for a potential run.

"Raise a lot of money," he said, emphasizing the difficulties of a presidential bid.

"This has been a brutal, tough process at least since 1800, and it hasn't gotten any less brutal. It probably shouldn't," he said. "If you're not tough enough to get to the presidency, you're not tough enough to be president."

I doubt Gov. O'Malley could use any of the advice Newt Gingrich could give him about being a successful presidential candidate, but if he needs some advice on how to sell books while pretending he wants to be president, I'm sure Gingrich could be very helpful in that regard.