The Republican presidential campaign is turning into a race for delegates, and if Republicans held their nominating convention today, the party's 2012 presidential nominee would be decided in a convention fight.

No one candidate was able to sweep the early states, and now we're left to run the numbers on how long, exactly, this whole thing will take to sort itself out.

Barring a shift in momentum so dramatic that three candidates drop out, the finale of the 2012 GOP race will center on the pool of Republican partisans who will actually, mechanically, decide the nominee by voting at the Republican National Convention in Tampa, Fla., this August.

If Mitt Romney stays afloat as the GOP leader, the biggest question concerning delegates will be: Can Santorum, Gingrich, and Paul stay in the race long enough, and win enough delegates for themselves, to suppress Romney's count and deprive him of a winning delegate total?

If it looks like they can, the Republican Party will head toward its Tampa convention without a nominee-unleashing a deluge of lobbying and deal-making on the part of each campaign.

Mitt Romney (105) currently leads Rick Santorum (71), Newt Gingrich (29), and Ron Paul (18) in our ABC News delegate estimate. However, those numbers include predictions for delegates that won't technically be "awarded" to any candidate.  Iowa, for instance, will leave all of its 28 delegates "unbound," free to support any candidate they choose, regardless of Santorum's win in the state's caucus. Until those delegates are chosen in June, ABC and other outlets have predicted that most will support Santorum, with the rest backing Romney.

Strictly counting "bound" delegates-those required, by rule, to support a particular candidate based on primary-night vote results-Romney (73) still leads Gingrich (29), Paul (8), and Santorum (3).

In order to win the nomination, a candidate will have to secure the votes of 1,144 delegates at the August convention-a majority of the total pool of 2,286 delegates. If Santorum, Gingrich, and Paul combine for more than half of the GOP's total delegates, Romney will not be able to win the nomination before August.

In that deadlock scenario, campaigns would lobby more than 400 "unbound" delegates for support. Much like Democratic "superdelegates" in 2008, the "unbound" Republican delegate votes would become very consequential. Some states only "bind" their delegates through the first round of voting at the Republican National Convention, and after that first round of voting, a delegate-battle-royale would ensue on the floor of the Tampa Bay Times Forum.

In other words: Delegate Apocalypse.

If Republicans ignored the remaining states and held their convention today, the nominee would be decided in a floor fight. Romney's 73 bound delegates fail to constitute anywhere near a majority of the total 243 delegates representing Iowa, New Hampshire, South Carolina, Florida, Nevada, Colorado, Minnesota, and Maine.

It will take any candidate a long time to get to 1,144. Even if Romney, the delegate leader, sweeps every single state, he won't be able to reach 1,144 in ABC News' delegate estimate until April 3.

Counting only "bound" delegates-those who can't change their minds later-Romney won't be able to seal the nomination until at least April 24. Should Santorum overtake Romney, it would take him even longer to win.

So while the big delegate storyline, at present, is who's ahead and whose total looks more promising, at some point more questions may arise over whether any candidate can win the nomination before Tampa. If the campaign continues apace, the nomination will be contested at the Republican convention.

Each state has its own rules for awarding delegates, and, after a 2010 decree by the Republican National Committee, most states will award delegates proportionally-making it much, much harder for a single candidate to take a commanding lead. Members of the Republican National Committee's rules committee approved this mandate, in August 2010, in a moment of regret over John McCain's loss in 2008.  Party leaders figured that the protracted Democratic contest had ginned up national interest in Barack Obama, and they wanted to mirror the drawn-out process Democrats had used.

If the GOP's 2012 nominating contest ends messily, the Republican Party will have itself to thank-or blame.