Trump hasn't closed the deal—WE still decide who the nominee will be

Delegates to the Republican National Convention will gather in less than two months and are expected by most to nominate businessman Donald Trump for president. But it's not quite so simple or certain – Trump will still have one last sales job ahead of him, persuading the delegates to choose him at the convention before he can claim the nomination.

This is because each and every delegate has complete freedom to vote their conscience at the convention, including who the party's nominee should be. This may come as a surprise to many, particularly those who are reading about Trump's recent win in the Washington state primary and how close he is to "clinching" the Republican nomination.

But the nomination cannot be "clinched" or won until the delegates actually vote. And even if delegates were obligated to obey the "will of the people" as expressed through primaries and caucuses, Trump's claim on the nomination would still be dubious at this point – at present he has only won roughly 43 percent of all primary and caucus votes cast, and would need to net more than 3.5 million voters in the June 6 primaries to win even a bare majority of all votes cast.

But it will in the end be the delegates to the Republican National Convention, which has protected the right of delegates to vote their consciences since the first convention in 1856, who decide if Trump will be the party's nominee.

The first Republican convention adopted rules requiring each delegation's chair to announce the vote of the delegates, which was understood to mean each delegate's vote was to be announced and recorded as they wished. The 1860 and 1868 conventions saw delegates stand up and challenge the votes announced by their delegation chairs, and in all cases the convention recorded the delegates' votes according to their wishes and regardless of any state party rules or instructions to bind delegates votes.

At the 1876 convention, there was extensive debate over whether to accept the binding of delegates, and in the end the delegates voted to reject binding. At the 1880 convention, language was added to the convention rules to block any and all efforts to bind delegates, and on over 200 occasions since these conscience protections have been invoked, including against state laws attempting to bind delegates to primary results.

In 1976, the campaign of President Gerald Ford managed to get the convention rule amended to permit binding of delegates as part of a strategy to block former California Gov. Ronald Reagan from getting the nomination. In 1980 this language was removed, and the temporary rules for the 2016 convention include almost exactly the same language as the rule first added in 1880.

Whether directed by state party rules or state law, the Republican National Convention has never, with the exception of 1976, forced delegates to vote against their conscience. So if Trump wants to be the Republican nominee, he will have one last sales job of persuading the delegates to nominate him – and this time he'll need a majority, something he hasn't managed so far in caucus and primary votes.