The main focus has been on delegates so far. However, because of the winner take all states those figures are skewed. When the popular votes alone are taken into account, Trump currently has 37% of the popular vote and Cruz 27%; all others have 36%.
Assuming that Trump and Cruz are the only two real potential nominees, if a brokered convention were held now, and if delegates voted as per the popular vote, then Trump would have to get at least 36% of the delegates currently committed to the other candidates (other than Cruz) to switch to him. Given that at least 30% of Republicans say they would not vote for Trump under any circumstances, if we assume that 30% of the delegates currently for others goes to Cruz, then Trump would have to convince about 52% of the remaining delegates to switch to him.
That is not impossible, but given Trump's increasing negatives, I find it harder and harder to believe he could accomplish that. The remaining primaries will change that of course, but so far Trump may have an uphill path at a brokered convention even under existing rules.
