60 IN '14:

That party seems likely to lose seats in Montana, South Dakota and West Virginia, where it cannot find find strong candidates.

The GOP will probably need to capture six Democratic seats in 2014 to grab the majority, as Newark mayor Cory Booker is well positioned to win the seat held by interim Sen. Jeff Chiesa (R-N.J.) in a special election. Democrats hold a 54 to 46 advantage, counting two independents who caucus with them.

But they must also defend four vulnerable incumbents and the seat soon to be vacated by Sen. Tom Harkin (D) in Iowa, a swing state.

Sens. Mark Pryor and Mark Begich, Democrats from Arkansas and Alaska, where Obama lost badly in 2012, are in greatest danger. Sens. Mary Landrieu (D-La.), a three-term survivor perpetually on the GOP target list, and Kay Hagan (D-N.C.), who had a solid lead in a recent Public Policy Polling survey, will also have competitive races.

Pryor is seen as the most vulnerable, though Begich is a close second.

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