An open Republican convention would not only leave the party’s presidential nomination hanging in the balance until July: The question of a running mate for the nominee, a vitally important component of any campaign, could also remain unanswered until the GOP meets in Cleveland, or perhaps even later.

This variable could create an added element of chaos to an already turbulent convention, possibly forcing a last-minute scramble to name a vice presidential candidate for the freshly minted nominee, or setting up a battle on the convention floor among multiple wannabe running mates.

Either way, there would be no precedent in the modern political era for what might transpire, and no playbook for the Republican Party to follow.

“Since the advent of pre-named tickets heading into the convention, we haven’t had a situation like this,” said Ryan Williams, a GOP strategist and former aide to Mitt Romney. “It’s absolutely uncharted territory.”

The onus to chart a path would fall first on the candidates themselves, who could opt to break with tradition and name their choices without the nomination locked up. This would not be unprecedented, and not without risk, however: They could lose leverage to strike a deal at the convention, appear presumptuous, or alienate delegates with their pick.

Conversely, the number-two slot could be used as a bargaining chip to strike a deal to win the nomination. If a nominee emerges without first forging some sort of unity ticket, however, the selection responsibility would fall to the party, either through a vote on the floor or by giving the nominee time to make his own last-minute pick.

“If a candidate were very close on the first ballot, but doesn’t have 1,237 delegates, the greatest single tool they have on the second ballot is to bestow the vice presidency on someone,” said one Republican strategist.

There is even a chance that the nominee could delay picking his running mate until after the convention to allow for the lengthy vetting process that has become standard for vice presidential picks.

How the drama plays out will be highly consequential, yet the campaigns have not begun to publicly contemplate potential scenarios. John Weaver, campaign manager for Ohio Gov. John Kasich, declined to discuss whether his team is already strategizing around such considerations, but he said the process would likely set a precedent.

“Given that this has been a cycle where the old rules -- or the old conventional wisdom, or, hell, even new conventional wisdom -- they don’t apply, I would say the process by which a candidate might pick someone, those rules are probably out the window as well, or should be,” Weaver said.

The process of choosing a running mate is typically a careful and deliberate one, among a presumptive nominee’s key political tests leading into the general election. A VP choice can affirm an ascendant campaign, as with Barack Obama’s pick of Joe Biden in 2008, or fail to boost a flailing one, as with John McCain’s selection of Sarah Palin that same year. With these stakes in mind, campaigns in the modern era vet potential candidates extensively, interview them, and weigh all political pros and cons.

A nominee-in-waiting then announces his decision with a tightly scripted rollout, timed to build toward a triumphant joint appearance at the party convention. Mitt Romney, for example, announced Wisconsin Rep. Paul Ryan as his running mate in Norfolk, Va. – using the USS Wisconsin as a dramatic backdrop -- roughly three weeks before the national convention in Tampa, Fla.

In that gathering, and at all others in recent memory, the vice presidential pick has been affirmed by acclamation. But the current rules would subject a vice presidential choice to the same nominating process as the presidential nominee: If there is more than one candidate for the office, a roll call vote of delegates is taken. However, the rules are often rewritten prior to each convention, so it cannot be known at this stage whether this procedure would be used in an open convention.

Meanwhile, there is no playbook to guide the proceedings.

The closest modern parallel occurred during the 1976 Republican primary, when Ronald Reagan and President Gerald Ford fought for the nomination all the way to the convention in Kansas City. At that time, vice presidents were not picked prior to the quadrennial gathering — but Reagan broke with tradition and, without having locked up the nomination, announced his would-be running mate three weeks in advance of the meeting.

Reagan’s play was highly strategic. His pick, Sen. Richard Schweiker of Pennsylvania (pictured), rounded out the hypothetical ticket with his more moderate profile; at the same time, Schweiker could bring his state’s uncommitted delegates to Reagan’s side. The surprise move shook up the dynamic of the race, in which Ford was seen as holding the advantage going into the convention.

“What Reagan did was really revolutionary,” said Craig Shirley, who wrote a book, “Reagan’s Revolution,” documenting that campaign.

But the former California governor came up short when his camp proposed changing the convention rules to force Ford to name his own running mate in advance. Ultimately, the gambit didn’t work, and Ford went on to win the nomination with Sen. Bob Dole as his VP choice.

That situation was far different from the one Donald Trump, Ted Cruz and John Kasich could face at this year’s convention, however. The vice presidency has evolved since 1976 from something of an afterthought to a key fixture of the presidential race and a crucial weathervane for a candidacy.

In this context, said professor Joel Goldstein of St. Louis University, an expert on the vice presidency, a last-minute running mate pick at the convention seems almost unthinkable.

“The idea that you would choose the vice president in a few hours, when everybody is tired and maybe some people are celebrating and hungover?” Goldstein said. “It’s kind of absurd that at that point you would choose somebody who in the past administrations has played a consequential role and is going to be a major, visible person in the campaign and would be a heartbeat from the presidency.”