The GOP vice presidential nominee in 2012, Wisconsin Rep. Paul Ryan, told NBC News that he will not be a candidate for president in 2016.

I have decided that I am not going to run for president in 2016," Ryan said in a phone interview, noting that he is "at peace" with the decision he made "weeks ago" to forgo a bid for the White House.

"It is amazing the amount of encouragement I have gotten from people - from friends and supporters - but I feel like I am in a position to make a big difference where I am and I want to do that," he said.

The nine-term congressman believes he can make that "big difference" in his new role as chairman of the influential House Ways and Means Committee rather than as a presidential contender.

The committee will meet Tuesday to kick off the new Congress. By announcing that he'll pass on a White House run, Ryan hopes to demonstrate that he'll devote his "undivided attention" to the committee, although he admits that it will be "bittersweet not being on the trail" as a candidate this upcoming cycle.

Ryan, who is married with three young children, said he reached his decision over the holidays last year, well before Friday's news that his former running mate, Mitt Romney, is once again eyeing a presidential bid.

"It is no secret that I have always thought Mitt would make a great president," he said. "As for his plans for 2016, I don't know what he is ultimately going to do and the last thing I want to do is get ahead of his own decision making process."

The congressman would not throw his support behind any potential 2016 presidential candidate during the interview, saying that any endorsement would be "premature."

But, Ryan added, he believes that a Republican can "absolutely" win.

Since 2012, Ryan has kept a lower profile than most other Republicans mentioned as 2016 presidential candidates.  Few visits to early primary states and no staff moves that would suggest he was interested in running.  His focus has been on developing policy alternatives, including budget and entitlement reforms.

With Mitt Romney almost certainly ready to make another run for president, the 44-year-old congressman, who has been serving since he was 26 years old, may feel that his time has not come yet.  He will chair the most powerful committee in Washington – Ways and Means – where there will be plenty of action over the next few years.  There is also the possibility of a run for higher office a few years down the road.  Governor or Senator Ryan may be in a better position to run for president in 2020 or 2024.

Ryan's bid would have been a long shot.  With other prominent conservatives running, he would have been a second-tier candidate at best, fighting to survive early primaries and scraping for money.  And while no one doubts his capabilities, he is not an inspiring speaker or dynamic personality.  Voters might admire his cerebral attention to the issues, but otherwise, he doesn't excite voters the way a Ted Cruz or Rand Paul might.

If a Republican presidential candidate wins in 2016, Ryan could be tapped for a cabinet position.  But it would be a big step down from Ways and Means, and Ryan appears to be angling to move up, not down or sideways.