GILBERT, Ariz. – Should Mitt Romney follow the advice of one of his top backers, former New Hampshire governor John H. Sununu, that “the winning choice is the dull choice” when it comes to a running mate?

Businessman and former GOP presidential candidate Herman Cain. (Win McNamee/Getty Images)

The businessman and former GOP presidential hopeful – who dropped out of the race in December amid allegations of sexual harassment and an extramarital affair — said in an interview here Tuesday night that the best choice for Romney is a VP who will energize the GOP ticket.

“I just want it to be someone that people can be excited about,” Cain said after addressing the annual dinner of a local tea party group. “I think that enthusiasm gap is going to be the biggest challenge that we’re going to have, because of the primary, because of all of the unpredictability. I just want to see someone who’s going to bring some excitement to the ticket.”

Might Sen. Marco Rubio (R-Fla.) be that kind of choice?

“He would be one,” Cain said. “He would bring some excitement to the ticket. But here again, you’ve got to consider what he wants to do versus what the nominee wants to do.”

How about Cain himself?

“There again, we’ll have to see if we get to that point, because when I have offered my assistance to the candidates, I wasn’t looking for anything, I didn’t ask for anything and they didn’t offer anything,” he said. “So, it’s just too premature to say whether something like that would make any sense or not.”

Cain, who endorsed former House speaker Newt Gingrich (R-Ga.) ahead of January’s Florida primary, has been keeping busy on the public-speaking circuit even though he is no longer a presidential hopeful.

On April 16, he plans to hold a Tax Day rally in Washington, D.C., where “we are going to be launching something called – and this is an exclusive – Cain TV,” he said Tuesday. Cain also plans to release a new book on his 9-9-9 plan later this year.

At Tuesday’s Arizona Liberty Project event, Cain kept the crowd of about 200 Republicans and tea party supporters rapt with a 40-minute address in which he urged them, among other things, to “stay informed, because stupid people are running America,” as well as to rally behind whoever wins the GOP nomination.

“When John McCain was our candidate three and a half years ago, six million conservative Republicans stayed home,” Cain told the crowd. “If your favorite nominee does not get the nomination, get over it. Focus on the mission. My favorite person isn’t in there either – me.”

He added that “this is about staying focused on the mission” rather than about electing “a perfect candidate.”

“So when you hear people say, ‘Well, I don’t like Romney, so I’m not going to do anything,’ you tell them that’s a vote for Barack Obama,” Cain said.

Asked whether he would urge Gingrich – who for weeks has been lagging far behind in the race – to drop out of the race, Cain said that the decision is up to the former House speaker alone, and that the two have not spoken for the past month or so.

“Well, he’s going to have to make that decision,” Cain said. “And I know it’s a tough decision, because the decision to get out of the race is really tougher than the decision to get in the race. So I know what he’s wrestling with. So, I really can’t say whether he should or he shouldn’t, because there are pros and cons both ways. But I know that he is a true patriot, and he’ll make a decision in due time.”

After his brief time atop the polls and then his sudden freefall – which Cain still attributes to “a coordinated character attack” that his camp is still investigating – the former Godfather’s Pizza CEO has all but receded from the presidential spotlight.

But he retains a loyal following among tea party backers, including the Arizona crowd, which gave him several standing ovations Tuesday night and cheered him when he told them that “some of the most inspiring words I’ve ever come across came from a movie that I have never seen ... Pokemon.

“We must remember the words from Pokemon: ‘Life can be a challenge. Life can seem impossible. It’s never easy when there’s so much on the line. But you can make a difference. There’s a mission just for you. Just look inside and you will find just what you can do. Just look inside and you will find just what you can do.’ ”

After the event, Cain was swarmed by supporters, including one man wearing a black leather vest who patted Cain on the back and shook his hand.

“Sir, I had lost hope, but you have inspired me and I’m ready for the fight,” the man said.

“Thank you, sir!” Cain said. “Don’t lose hope. We can do this. We can do it.”

A few moments later — just as he’d done in his days as a GOP hopeful – Cain hopped into a black SUV and sped away.