Jonathan Chait beat me to it. From "Have House Republicans Extended the Economic Recovery Into 2016?" (my emphasis):
Rather than stimulating economic growth through short-term
deficit spending, Republicans have instead kept a fiscal vise that,
according to macroeconomic forecasters, has held the recovery to a
painfully slow rate of growth.
But at the same time, the fiscal vise has had the likely side effect of extending the duration of the recovery.
Last week, JP Morgan chief economist Michael Feroli published a
short paper demonstrating that the speed of economic expansion since
World War II has correlated inversely with its length. “Somewhat
counter-intuitively,” he concluded, “the shortcomings of this expansion —
an initially high unemployment rate and slow growth — are virtues when
thinking about how much longer the expansion will run.”
That would put the recovery on schedule to expire in 2018, just in
time to position Republicans to benefit from another angry midterm
wave, but not fast enough to win the White House.
The problem for Hillary, then, is how to avoid the fate of George H. W. Bush, who suffered a recession and was turned out of office after only one term.