Donald Trump is currently leading the Republican primary race by an average of 20 percentage points. And on Monday MSNBC pointed out that no Republican candidate with a national lead this big in late December in the modern era of polling -- since 1972 -- has ever lost the nomination.
However, the case rests on only three Republican primaries in which someone led by 20 points or more in December. Ronald Reagan led by more than 20 points in December before the 1980 election, as did Bob Dole in 1995 and George W. Bush in 1999.
In the remaining seven contested Republican primary elections in the last 44 years (Richard Nixon ran unopposed in 1972), five included an incumbent president or vice president who was running -- and historically speaking, primary elections favor incumbents. Gerald Ford in 1976, Ronald Reagan in 1984, George H. W. Bush in 1992 and George W. Bush in 2004 all ran as sitting presidents. In addition, Bush Sr. ran as a sitting vice president in 1988.
And while it may hold true that candidates with 20 percent of the vote or more in the December before the election go on to win the nomination, candidates who have had less than 20 percent have also gone on to win. In the December before the 2008 election, an NBC/WSJ poll found that John McCain was in fourth place and 6 points behind front-runner Rudy Giuliani. And in 2012, Mitt Romney was tied with Newt Gingrich for first place at 28 percent, according to a CNN/ORC poll. Both went on to win the nomination.
While it's unprecedented in the GOP primary to lead by 20 points or more and not win the nomination, it has happened in the Democratic primary. Just as recently as December of 2007, Hillary Clinton led Barack Obama by 22 percent, according to a WSJ/NBC poll.
One important thing to keep in mind is that there is no such thing as a national primary election. The other is that the primary race is still in flux and polls this early should not be relied on to make any determinations of the final outcome.
After a week of several national polls touting Trump as the clear front-runner, a Quinnipiac poll released Tuesday provides some evidence that underscores the volatility of this race. The poll shows Trump ahead of Sen. Ted Cruz (R-Texas) by just 4 points with 28 percent of the vote.
And 58 percent of Republicans in the Quinnipiac poll say they might change their mind on who they're voting for before the election.
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