With mainstream Republicans struggling to overcome the rise of outsider candidates, some say the party could face something it hasn't seen in nearly 70 years: a brokered convention.
The term refers to a condition in which no candidate has the required amount of delegates to secure the nomination. The party then takes the battle to the floor where a nominee is decided.
The fractured nature of the race leading up to the 2016 nomination has Greg Valliere, who as chief political strategist at Horizon Investments is one of the leading voices on the Wall Street-Washington connection, thinking that a brokered convention could happen for the first time since 1948.
"A lot is at stake," Valliere said Tuesday at the Schwab IMPACT 2015 conference in Boston. "I can't tell you tonight who the winner will be."
He said Donald Trump probably won't be, because voters don't want to "hear him say for the next year that everything stinks." Nor does he give Ben Carson much credence.
Instead, he thinks the race will come down to five candidates who will battle it out among mainstream GOP voters (in ascending order).
5. Chris Christie, the New Jersey governor who "used to be viewed as coarse and rude and vulgar. He's a pussycat compared to Trump" and has scored on the unlikely issues of entitlement reform and drug abuse.
4. John Kasich, the Ohio governor who like Christie has lagged in the polls but is "a complicated guy but is not reflexively right-wing. One major problem: Democrats like him."
3. Jeb Bush. The former Florida governor and scion of the political dynasty has been counted out in various quarters but still has a tremendous fundraising edge.
2. Ted Cruz. The senator from Texas is "ferociously conservative" and "fiercely ambitious" as well as a "great debater." "He is despised by Republicans in Washington ... and he wears that as a badge of honor," Valliere said. "If Trump were to really start to fade, then I think the beneficiary would be Ted Cruz."
1. Marco Rubio, who's become the trendy pick lately to emerge from the pack. In NFL draft terms, the Florida senator is "the best athlete available."
"There's no question about who is the best talent in the Republican field," Valliere said. "He's a great speaker (with a) very upbeat story, a Reaganesque story, filled with hope."
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So how does it all shake out?
Valliere said that if the race does come down to the GOP convention, which will be held July 18-21 in Cleveland, Bush could emerge as the choice due to his staying power.
Ahead of Tuesday night's debate, polling has Trump and Carson running neck and neck with the RealClearPolitics average putting them at 24.8 percent and 24.4 percent, respectively. Rubio is next at 11.8 percent, Cruz has 9.6 percent and Bush is fifth with 6 percent. No other candidate pulls more than 3 percent.
However, Valliere cautioned that the outlook is cloudy.
In particular, he said there is a "crisis in the polling industry. I don't believe any polls anymore."
That's because polling agencies rely on land lines for calling, making the surveys less representative in an age when so many people use cellular phones, he said.
"In race after race, poll takers have gotten it wrong," Valliere said.