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Has the GOP hit a tipping point?

There is no denying that in the final days leading up to election day, the polls have tightened in North Carolina and even New Hampshire, two states where Democratic incumbents had been able to maintain a consistent edge throughout this election cycle. Yet, despite these campaigns becoming more competitive, they do not in practice create more paths for the GOP to gain Senate control.

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There are arguably nine Senate races in play that can be strung together in a linear continuum based on their probability of going red or blue. And along that continuum is a tipping point where one party wins enough states that the remaining races in question break disproportionately in its favor, giving it control of the upper chamber.

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Republican wins in either New Hampshire or North Carolina on election night would be an early death knell for the Democratic majority in the Senate. More realistically though, the indication of which party will ultimately be victorious will be who wins at least two states among Iowa, Colorado, and Kansas — the tipping point trifecta.

The GOP needs a net increase of six seats to take control of the Senate next Congress. They should easily win West Virginia, Montana, and South Dakota — these are like the free spaces in the middle of Bingo boards for the Republicans.

They also have the polling advantage in several other races. But most GOP candidates in the other battleground states are still close enough to the margin of error to allow for unexpected outcomes on election night.

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Republicans point to recent surveys showing disapproval of President Obama's handling of ISIL and the Ebola outbreak combined with the tightening races in the Tar Heel and Granite States as evidence that the elections are finally nationalizing and at least a small wave is approaching.

Democrats, for their part, are placing their faith in what they consider to be a better ground game geared toward exceeding traditionally sub-par midterm election turnouts, primarily by boosting minority voting. While the Democrats have had a discernible get-out-the-vote advantage throughout the Obama administration, this argument mirrors the hollow one that Mitt Romney's supporters made in 2012, in which they convinced themselves that the polling was skewed against Romney due to inaccurate turnout assumptions.

Whichever narrative proves to be true next Tuesday will determine which party reaches the tipping point.

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That brings us back to Iowa and Colorado, where these two competing narratives are most clearly on display. In these races, the GOP candidate is up by 2.1 percent and 3.6 percent, respectively, according to RealClearPolitics, but the two parties are trading barbs over the significance of early voting tallies and whether Colorado's statewide use of mail-in balloting for the first time in a partisan contest muddles the picture further.

The biggest headache for the GOP could be the toss-up in Kansas, where long-time incumbent Senator Pat Roberts is caught in the middle of the latest battle of the broader war between the establishment and conservative wings of the party. Republicans risk an unforced error if they fail to unite behind Roberts and hand his seat to independent candidate Greg Orman, who would likely caucus with the Democrats if his seat became determinative of Senate control.

Even after one of the parties wins at least two out of Iowa, Colorado, and Kansas, it may still have to wait awhile before officially being crowned the winner. With runoffs virtually guaranteed in Louisiana and Georgia on December 6 and January 6, respectively, Senate control very well could require a victory in at least one of these contests. Once the tipping point is hit on election night though, there will no longer be any doubts over which party clearly has the momentum.

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Commentary by Stephen A. Myrow, managing partner of Beacon Policy Advisors LLC, an independent policy research firm based in Washington, DC, and served as Chief of Staff to Deputy Secretary of the Treasury Robert M. Kimmitt in 2008-2009. Follow him on Twitter @smyrow.