The growing consensus among Republican National Committee superdelegates is that Romney will be the party's presidential nominee.

Superdelegates are special party delegates who can vote for whomever they please at the national convention, regardless of primary or caucus results, but there are only 120 of them.

Although there still 18 primaries left to go and roughly 1,000 delegates who have yet to vote, many Republican superdelegates find the math stacked up against Romney's remaining opponents, Rick Santorum, Newt Gingrich and Ron Paul, who trail the former Massachusetts governor by a significant margin.

According to Politico, Romney has racked up 660 delegates, Santorum has 81, and Gingrich has 135. Sen. Ron Paul (R - Texas) doesn't really have a chance at this point with only 51 delegates, as he is too far from receiving the necessary 1,144 votes needed to secure the nomination.

Even among the superdelegates supporting Romney's opponents, there is a sense that Romney's nomination is a foregone conclusion.

I would be surprised if Romney doesn't get the number he needs, said RNC member Jeff Johnson, of Minnesota, who supports former House Speaker Newt Gingrich, the AP reported.

RNC member Bob Bennett, of Ohio, who has not publicly endorsed any candidate yet, even though he supported Romney in 2008, believes the Republican race is no contest.

Look, Gov. Romney's going to be the nominee, and he's going to have enough votes, Bennett told AP.

The Associated Press conducted a poll of 114 superdelegates this past week, finding that Romney has already secured 35 endorsements, while Santorum has only four, Gingrich has two and Paul has one.  

Regardless, Santorum is anticipating a strong showing in the April 24 primary in his home state of Pennsylvania, where he served as Senator for 12 years, as well as in the upcoming remaining Southern state primaries, where he is expected to appeal to social conservatives.

He should go into those states as the front-runner, said Texas GOP chairman Steve Munisteri, who has yet to endorse a candidate, the AP reported. If he can win Pennsylvania, he'd then be able to put a streak of five or six wins together based on all the Southern states holding primaries.

Other RNC members, however, are hoping for the primary race to end, so that the nominee can start focusing on defeating President Obama in November, but it is not likely to end quickly unless Romney's opponents step down.

The decision to get in or get out of a race is an extremely personal decision, said RNC member John Ryder of Tennessee, who is neutral, the AP reported. He's got to decide when he thinks it is no longer politically valuable to continue.

It is very hard to see any path for Sen. Santorum to the nomination. It is very hard to see any path for Speaker Gingrich to the nomination, Ryder added. But they and their supporters have to make that final call.