WASHINGTON – Chester County Republican Ryan Costello has been in Congress for just over a month, but Democrats are already hoping to end his House career.

Democrats' national congressional campaign arm on Wednesday named Costello to its list of "one-term wonders," – 15 GOP freshmen that Democrats hope to oust in 2016.

"Democrats are on offense this cycle," said Josh Schwerin, a spokesman for the Democratic Congressional Campaign Committee. "We will work tirelessly to highlight how out of step Congressman Costello and other 'One-Term Wonders' are with their constituents."

But the list did not include another local Republican freshman, South Jersey's Tom MacArthur, even though Democrats have long targeted his Burlington and Ocean county district. Democrats won the swing seat in 2008 and launched some of their most aggressive attack ads of the last election there last year in trying to stop MacArthur.

Instead, they appear to be focusing for now on Costello, who represents a moderate Chester County-based district. Democrats have long seen the Republican-leaning district as one that is still within their reach – President Obama lost it by a mere three percentage points in 2012 -- but they have failed to make much headway there in House recent races. The Democratic nominee has lost by double digits in the last three races.

"Nancy Pelosi and House Democrats clearly missed the memo that their policies were roundly rejected at the ballot box last November," said Chris Pack, a spokesman for Republicans' House campaign arm. "We encourage House Democrats to continue championing their tax-and-spend policies because it will ensure that Ryan Costello will go into the election year stronger than ever as he continues fighting for Southeast Pennsylvania families."

Republicans have won every race in the Philadelphia area's suburban swing districts since the 2010 elections. If Democrats hope to gain ground, the surrounding political conditions may never be better for them than in 2016. Costello and MacArthur, both freshmen, are still building up their names, and they'll be running for re-election amid a presidential contest likely to bring out Democratic voters in both Pennsylvania and New Jersey.

Once House incumbents are entrenched, they become difficult to unseat.

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