Marco Rubio is the biggest Republican star in Congress -- conservatives started talking a "Rubio 2012" presidential campaign even before he was elected senator -- but, like Hillary Clinton when she first came to the Senate, he has refused all national television interviews since being elected.
ABC News embedded with Sen. Rubio -- in the cramped basement office he calls "the bunker" and with tea party activists in Florida -- for a rare behind-the-scenes look at the life of Washington's most celebrated freshman.
In wide ranging series of interviews, Rubio talked about the issues and his plans for 2012, and had harsh words for those on the far right who call President Obama a Muslim and question whether he was born in the United States.
Rubio firmly rules out running for president in 2012, but is far less definitive when asked about the prospect of being the Republican party's vice presidential nominee.
"I don't think I want to be vice president in 2012 because I'm focused on this job as a U.S. Senator," Rubio said. "I certainly feel that way right now."
Rubio is such a junior -- he ranks 95th out of 100 in seniority -- that he hasn't even had a chance to choose his permanent office yet. So, for now, he shares a windowless space in the basement below the Capitol complex, right across from the Senate stationery store.
In the Senate, where few things count more than seniority, freshman senators are usually seen but not heard. Rubio says he understands that, but he doesn't plan to lay low for long.
"The issues that led me to run are front and center," Rubio said. "And I can't just say, 'Well, I'm going to sit out these issues because I'm working on some deferential plan to ultimately fit into the Senate.'"
He's already taking a stand against his party leadership, voting against a government funding plan supported by Majority Leader Mitch McConnell and Speaker of the House John Boehner because, he said, it didn't cut spending enough.
Rubio says he's prepared to buck his party leadership again on government spending when the issue of raising the national debt limit comes up later this spring.
Republican leaders have suggested they will demand a vote on a balanced budget amendment before holding a vote on whether to raise the debt limit. Rubio says that is not enough.
"It certainly isn't enough. A balanced budget amendment doesn't ultimately deal with the fundamental issue that we owe almost $15 trillion and growing, with no real plan to address that moving forward," he said.
He wants a comprehensive plan to cut spending and government regulations before he'll support raising the debt limit, he said.
"The reality is our government spends money it doesn't have," Rubio said. "It's doing it at an alarming pace and there's no plan to stop it in the near future."
Rubio had harsh words for Obama on government spending (too much of it) and Libya (for not intervening earlier), but he was also critical of conservatives who question the president's religion and his status as a native born American citizen.
"That's a waste of time," Rubio said. "He says he's a Christian. He's a Christian. And I do believe he was born in the United States. And I don't think any of those things are the reason why America's in trouble.
"America's in trouble because it spends more money than it takes in and it better do something about it now or we are all going to pay a terrible price," he said. "We are going to lose the essence of the greatest nation that's ever existed."