Republicans have a secret weapon in their bid to win back control of the House of Representatives this fall: low-hanging fruit.

An astounding number of Democrats – 68, to be exact – currently represent districts that are “naturally” Republican, while only eight Republicans hail from Democratic districts. With the national climate already favoring them – thanks to surging unemployment and popular frustration with the ruling Democrats – this imbalance creates the potential for an extra-large GOP wave in November.

These numbers are based on the nonpartisan Cook Political Report’s Partisan Voting Index, an excellent barometer of a congressional district’s partisan leanings. A district’s PVI is derived by comparing the performance of presidential candidates nationally with how they do in each district. So if a district has a PVI of D+4, for instance, it means that the Democratic presidential candidate performed 4 points above his national average in the last two cycles.

Of the 68 Democrats who represent GOP-friendly districts, a whopping 43 are from districts where the PVI is R+5 or greater. Much of this imbalance can be chalked up to the 2006 and 2008 elections, when Democrats harnessed the nation’s profound Bush fatigue to make impressive incursions into GOP territory.