The Last Time There Was a Contested Convention

The 1976 Republican Party primary wasn't as sealed up as it is now.

At the time, neither Ford nor Reagan had secured the number of delegates needed to get that "presumptive" title ahead of time, meaning that there was some bitter fighting up until the end of the first roll call vote on the convention floor.

"In 1976, there was a matter of about 150 uncommitted delegates and also a lot of wavering delegates on both sides," historian Craig Shirley told ABC News.

"Jim Baker, who was then Ford’s delegate wrangler, used everything he could -- it was all legal of course --- to attract the uncommitted delegates to support Ford on the first ballot in Kansas City," where the convention was held, he said.

Trips to the White House during the primary and prime seating at bicentennial celebrations were used as wooing factors, according to Shirley.

"Ford was the incumbent president, and they have the majesty and the aura of the presidency, so they had to use [those] as inducements for uncommitted delegates," said Shirley, whose book "Reagan’s Revolution" is about the 1976 election.

"It really was silent about what you could do to attract uncommitted delegates or any delegates," Shirley said.

"To this day, I have never known the White House to be used by either party the way it was in this campaign. I was furious," she wrote in the memoir, which was published in 1989. "The White House stands for something more important than partisan politics and uncommitted delegates -- or at least it should."