In recent weeks certain political pundits have been suggesting that there's a possibility of a brokered Republican Convention this year.
A brokered convention occurs when none of the candidates has won at least 50 percent of the pledged delegates by the time of their party's convention. This hasn't happened since the 1952 Democratic Convention when Adlai Stevenson was chosen to run against Dwight Eisenhower. It hasn't happened to the Republicans since 1946 when the Republicans chose Thomas Dewey to run against Harry S. Truman.
There was some similar scuttlebutt back in 2008 when Barack Obama and Hillary Clinton were running closely throughout the race. If neither of them had been able to carry a majority it would have gone to a brokered convention in which the party elite would choose the candidate rather than those who voted.
However the way the system has been set up for years-- with each state's primaries or caucuses being all or nothing affairs does not lend itself as readily to the likelihood of brokered conventions... especially not in the information age when momentum is a much stronger factor than it was in the early pre-telegraph, pre-telephone days of our country.
That has changed in some states starting with this election cycle. Some states are opting to go to a proportional allotment of delegates.
Historically speaking, whoever wins a state carries ALL that state's delegates regardless of how close the race might have been. So in Iowa where Rick Santorum won by 30 some votes, he'd carry ALL of Iowa's delegates.
To my knowledge Iowa is not a state where that changed but let's say it was-- instead of Santorum getting ALL of Iowa's delegates, the delegates would be split proportionally to the number of votes won by each candidate.
If enough states end up going to the proportional allotment of delegates in the future brokered conventions will likely become a bit more common.
Where things get hairy is that many times the candidate chosen by the party elite ends up being a candidate who did not actually run in the primaries. The name floated around in 2008 when it looked like Obama and Clinton might have split the delegates with neither of them getting a majority was not either of them... it was Al Gore.
Similarly, the names being floated around on the GOP side if this goes to a brokered convention are not Mitt Romney, Newt Gingrich, Ron Paul, or even Rick Santorum... some of the names rumored for consideration in the event of a brokered GOP convention include Wisconsin Rep. Paul Ryan and Indiana Governor Mitch Daniels (the chap who delivered the GOP rebuttal speech to Obama's most recent State of the Union address).
The logic behind choosing a candidate who did not run in the primaries is that if none of the candidates who ran in the primaries were strong enough to get that majority none of them are strong enough to face the other party's nominee in the general election so we should look at other possibilities.