If the Republican primary battle goes on the way it has, it may be difficult for Mitt Romney, to mathematically seal the nomination at any point, despite his strong lead in the race for delegates to the GOP convention.
Even after polls close on the last contest, held on June 26 in Romney-friendly Utah, according to an analysis by ABC News the former Massachusetts governor may still be short of 1,144 delegates - the magic number a candidate will need to secure the nomination.
Based on 2008 presidential-primary results, conventional-wisdom expectations, statewide 2010 primary results by county, and polls, a conservative estimate suggests Romney will end this primary season just shy of the 1,144 delegates he'll need to win.
Counting only "bound" delegates, those who are required by rule to support Romney at the Tampa convention based on vote results in their states, Romney could end up with fewer than 1,000 in the end.
All of that could change if momentum swings in Romney's favor - or if a candidate drops out. Those numbers are rough estimates based on the race's current trajectory.
So far, Romney can count 521 delegates in his corner, according to the latest ABC News delegate estimate. He is trailed by Rick Santorum (253), Newt Gingrich (136), and Ron Paul (50). Those totals include estimates of unbound caucus-state delegates.
The Republican Party, however, has its own version of Democratic superdelegates: members of the GOP who will attend the Republican National Convention in Tampa this August as voting delegates, not having been elected or appointed, but included by virtue of their party roles. In nearly every state and territory, the GOP chairman, RNC committeeman, and RNC committeewoman hold this status.
In all, 123 of these superdelegates will attend the Tampa convention - enough to push Romney over the edge if a majority of them support him. Romney already enjoys the backing of 33 of these automatic RNC delegates, included in the 521 delegates ABC News estimates he has won.
Hundreds more will be free to support any candidate in Tampa.
A total of 430 unbound delegates will vote at the Republican National Convention, including the 123 RNC superdelegates.
Those include delegates from territories like American Samoa and Guam, where Republican delegates voted to state their preference for Mitt Romney but will not be held to that declaration, according to the Republican National Committee. On top of those 430, Romney may not win the automatic backing of any delegates he wins in Illinois, where candidates present slates of delegates in each congressional district. Those delegates are technically able to change their minds later under the Illinois GOP's rules, according to the state party.
Counting only "bound" delegates, current ABC News state estimates suggest Romney leads with 390, ahead of Santorum (164), Gingrich (130), and Paul (24). Estimates vary among campaigns, media outlets, and the RNC, depending on which delegates are considered "bound" and "unbound."
Barring a breakout by Romney, a wearing-down of Santorum's underdog campaign, or Newt Gingrich's unexpected exit from the race, one of two scenarios appears likely:
1) With the support of RNC superdelegates, Romney narrowly wraps up the nomination before the national convention in Tampa.
2) Romney falls short, left to struggle with Santorum for the backing of unbound delegates in July and August, with hundreds potentially in play.