We're beginning to see the contours of the map House Democrats and Republicans will fight over in November. Redistricting, the 2010 Republican wave, and a dismally unpopular Congress are converging to create a volatile foundation for the battle over the House of Representatives, a fight both parties are girding for by reserving advertising time across the nation.

TV Ad Buys

Party committees in the House have already reserved more than $64 million in airtime in nearly 60 districts. Democrats have made two rounds of reservations totalling more than $46 million, while the NRCC this week announced its first set of reservations, totalling $18.2 million.

TV ad reservation spending, by House party committee (As of June 15) Democrats Republicans map Sources: Democratic Congressional Campaign Committee; National Republican Congressional Committee; Graphic by Ryan Morris

Unfortunately, your browser does not include SVG support, which is needed to view this interactive graphic. Please upgrade to Internet Explorer 9, or download another browser such as Chrome, Firefox, or Safari to view this graphic.

Figures provided by both the Democratic Congressional Campaign Committee and the National Republican Congressional Committee show the two sides have reserved more than $64 million in airtime in nearly 60 districts, spanning from New England to the Rust Belt to Florida and across the Mountain West. The purchases are the opening rounds of the spending decisions the parties will make this year, but they offer hints of the major battlegrounds to come.

(FULL COVERAGE: 2012 Battleground States)

The new set of maps coupled with the absence of an atmosphere conducive to a wave election has Democrats and Republicans in both offensive and defensive postures. The committees have reserved time in markets that cover all or parts of 37 Republican-held seats, 16 seats currently in Democratic hands, four newly-created districts, and two in which contraction forced an incumbent Republican and an incumbent Democrat into the same territory.

Democrats have made two rounds of reservations totalling more than $46 million. The NRCC this week announced its first set of reservations, totalling $18.2 million in 17 media markets. Both sides will make future reservations, and the money won't be locked down until just days before the actual advertisements are slated to run, allowing the parties to move money when a race breaks for or against them later this year.

For the first time in a decade, both sides will spend millions in newly-competitive seats in California, where an independent redistricting panel drew maps without considering incumbency. The DCCC has reserved nearly $4.8 million in airtime in the Sacramento market, while the NRCC has plunked down more than $3 million; the two sides will battle over four northern California districts held by Democratic Reps. Jerry McNerney and John Garamendi and Republican incumbents Dan Lungren and Jeff Denham.

Democrats have made major advertising buys in Florida, where a host of incumbent Republicans face difficult reelection fights. The DCCC has reserved time in the Tallahassee, Orlando, Tampa, Miami, and West Palm Beach media markets, hoping to unseat Reps. Steve Southerland, Daniel Webster, Bill Young, Vern Buchanan, Allen West, and David Rivera, and aiming to pick up a newly-created district in the Orlando area.

The party is also on offense in Illinois, where Democratic-controlled redistricting has put GOP Reps. Joe Walsh, Robert Dold, Judy Biggert, and Bobby Schilling in jeopardy. Democrats are playing defense in Illinois's 12th District, where Rep. Jerry Costello is retiring, and they're aiming to win an open seat held by Rep. Tim Johnson, too. Republicans are moving to protect their Illinois incumbents with early ad buys totalling more than $1.3 million.

Republicans are bullish on North Carolina, where the party's control of the redistricting process put both Reps. Larry Kissell and Mike McIntyre in redder territory. The NRCC has reserved more than $2 million to spend against the two Democrats, both of whom narrowly avoided losing in 2010.

Early Republican buys also take aim at Democratic Reps. Ben Chandler, John Tierney, Mark Critz, and Jim Matheson. Democrats are hoping to take back seats held by Reps. Dan Benishek, Chip Cravaack, Rick Berg, Charlie Bass, Frank Guinta, Jon Runyan, and Scott Rigell, all of which the party lost in the 2010 Republican wave.

The parties have left few potential pickups off their early lists. Most of the exceptions are covered by expensive Southern California markets, though Rep. Joe Donnelly's seat in Indiana and Rep. David Cicilline's seat in Rhode Island could be considered competitive and yet aren't on either party's list of initial targets.