Newt Gingrich: 'Highly implausible' I would be Romney's running mate

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."

While the former House Speaker was a presence in the GOP primary for a long time, outlasting several challengers, he nonetheless struggled to gain substantial traction, winning just two states, South Carolina and his home state of Georgia.

As he struggled to stay in the race, Gingrich's camp struggled to cobble together the finances to stay afloat.

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."

As for O'Malley, he dismissed any talk that he is eyeing a 2016 run, emphasizing his current efforts as head of the Democratic Governors Association.

"I haven't even thought that far," he said. "I'm focused on what I'm doing right now."