Not even the Weather Channel is safe anymore. Thanks to the explosion of money in politics and the imperative of reaching key voting blocs, political strategists are increasingly turning to cable television to spread a candidate’s message.

But buying the right package is still an art, and the delicate balance between cable and broadcast television advertising can mean the difference between a message penetrating an audience and an expensive one lost in the shuffle.

New campaign finance rules that have paved the way for millions of additional political advertising dollars have ensured that presidential campaigns and their associated Super PACs can purchase so much advertising time that, in some instances, a state’s entire inventory may be snapped up. This primary season, that has led campaigns to an increasing reliance on cable advertisements, which have come across a broader spectrum of channels than ever before.

Through the year’s first three Republican nominating contests—Iowa, New Hampshire and South Carolina— presidential candidates and the Super PACs backing them spent $32 million on television advertising. While the bulk of that advertising—a little under $30 million—came on broadcast television, the candidates also spent more than $2.25 million to run more than 68,000 individual ads on cable television, according to data from Republican ad buyers and NCC Media, a firm that represents cable companies and helps candidates place ads.

“Unlike a few cycles ago, cable is now seen as a viable tool to be used,” says Brian Walsh, president of the American Action Network, a Super PAC that backs Republican candidates.

Cable has asserted itself over broadcast as a significant presence in the daily lives of Americans. A decade ago, just four out of 10 minutes of television viewing happened on cable stations. Today, that number is closer to six in 10. And 90 percent of Americans pay for some form of television. The way cable systems are set up means advertisers can drill down below a standard broadcast media market to more accurately target the right voters.

“We can align our voter data or other metrics to determine what systems hold the concentration of what voters in certain areas,” says Tim Kay, NCC Media’s political director. “If elections are won by a few thousand votes, identifying them and targeting them becomes more important.”

During the Republican presidential contest, three different cable strategies have emerged: The Fox-only strategy put an enormous emphasis on Fox News Channel’s depth of reach among Republican primary voters. The broad-based strategy has tried to expand the electorate by targeting new voters who don’t otherwise watch Fox News. And the surgical-strike approach took advantage of key moments during the campaign to reach a broader audience and get more bang for a candidate’s buck.

Given the nature of the Republican electorate this year, it comes as no surprise that Fox News Channel has been the biggest recipient of cable ad dollars. About half of all cable advertisements in Iowa aired on Fox News, while 10 other networks aired 45 percent of the remaining spots. Almost every candidate aired advertisements on Fox, beginning in early July when Rep. Michele Bachmann began running small ad flights on the network’s channels in Cedar Rapids, Davenport, Des Moines, and Sioux City. Mitt Romney’s campaign ran cable advertising almost exclusively on Fox News in Iowa, to the tune of $151,000.

Rep. Ron Paul’s campaign made the biggest effort to appeal to a broader slice of the Iowa electorate. Paul’s campaign, which relies on irregular voters and disaffected populations who don’t otherwise turn out to cast ballots, targeted viewers on 20 different cable networks—channels as diverse as the Food Network, the Golf Channel, the History Channel, and Spike and FX, two outlets that cater to younger male audiences with sports and talk shows. Paul’s campaign even spent about $2,400 on 36 spots on The Weather Channel in the Columbia, Florence and Myrtle Beach and Greenville-Spartanburg markets in South Carolina.

Other candidates didn’t have the resources Romney or Paul brought to the advertising game. But one advantage of advertising on cable is that high-impact spots, when they become available, can sell for much less than broadcast ads. Former House Speaker Newt Gingrich took advantage of one of those rare moments; on December 29 of last year, Gingrich placed significant ad buys on ESPN and ESPN2 in nine Iowa markets. That day, the Iowa State Cyclones lost the New Era Pinstripe Bowl to Rutgers and the Iowa Hawkeyes were overrun by the Oklahoma Sooners in the Insight Bowl. Both games aired on ESPN, giving Gingrich relatively inexpensive access to every college football fan in Iowa.

Texas Gov. Rick Perry’s campaign bought cable advertisements in November and December for an even more specific audience tuning into the Big Ten Network, a station that broadcasts sporting events from around the Midwest (The University of Iowa is in the Big Ten). Buying sporting events gave both Gingrich and Perry access to overwhelmingly male, Republican leaning audiences—cheap, effective surgical strikes.

Even while cable is growing, broadcast television remains the dominant medium, according to advertising experts in both parties and the industry itself. And yet cable is playing a bigger role, especially for those who need demographic metrics to back up their investment.

“If I want to target viewers between the ages of 25 and 64 through cable news, I know that ‘The O’Reilly Factor’ reaches the most viewers for that age group,” says Laura Crawford, a media buyer at JDA Frontline, a Republican firm. “With cable we can microtarget not only age groups, but those who have interest in fitness, food, specific sports, and reality TV.”

Given the mega-budgets outside groups and the campaigns themselves are planning for key races across the nation, cable also plays a big role in establishing a narrative. Airing inexpensive ads is a cheap way to back up messages that come through in other media.

“It’s largely seen as a supporting tool. So if you’re running mail, you’re using cable to back up the mail. If you’re running broadcast, you’re using cable to back up the broadcast,” says Walsh. “You can use it to reinforce your broader message and/or in some cases microtarget your message to specific audiences.”

Walsh, who served as political director at the National Republican Congressional Committee in the 2010 cycle, pointed to Gov. Chris Christie’s successful bid in New Jersey in 2009 as one example.

Incumbent Democrat Jon Corzine had accused Christie of jeopardizing mammogram coverage in health insurance plans; Christie blasted back on cable. Christie’s response credited a mammogram with saving his mother’s life by detecting breast cancer early. The spot ran on cable channels almost exclusively targeted toward women voters.

And thanks to new and popular election laws, buying cable is becoming even more important as voters consider their options. In many states, absentee ballots begin arriving in mailboxes as much as a month before Election Day (In Washington State and Oregon, elections are conducted entirely by mail). With a growing percentage of Americans voting early, Election Day no longer takes place on one day—it takes place over four weeks. That presents a campaign with budgetary problems.

Walsh pointed to Phoenix, a television market that could have as many as five competitive Congressional elections, a competitive Senate seat and even a battle for the state’s 12 electoral votes. President Obama’s campaign strategists have indicated they believe Arizona’s growing Hispanic community will put the state in play this year.

If each campaign must pay $280 per gross ratings point on broadcast television, few are going to be able to sustain that spending throughout the voting period.

“How many Congressional, or even Senate, campaigns are going to have those kinds of resources at their disposal?” Walsh asked. Instead of a prolonged broadcast blitz, cable will become a more affordable answer.

Strategists who specialize in placing advertisements on television are finding it necessary to reconsider their methods thanks to rapidly evolving technology that is changing the way Americans consume media, broadly speaking, and watch television, more specifically. Industry research shows television viewership is rapidly declining; viewership this season is down almost 10 million over last season as more Americans begin watching programs on digital video recorders (DVRs) and on internet video-on-demand sites like Hulu.

DVRs are increasingly making their way into American households. Fully 44 percent of consumers have a DVR, up from 33 percent in 2008, according to Deloitte’s annual State of the Media Democracy survey released in early January. Meanwhile, almost one in ten consumers have canceled their paid television service because they can watch their preferred shows online, the survey found, while 15 percent say they will most likely watch all their television online in the near future. The percentage who say they will watch their favorite shows live, as they air on television, has dropped precipitously, from 87 percent in 2008 to 71 percent this year. Among the Millenial generation, those between 23 and 28 years old, the number who will watch television live—and thus sit through political commercials—falls to 59 percent.

Crawford, of JDA Frontline, sees the growth of Internet and DVR technologies as an opportunity to reach more voters in more targeted media. “The DVR allows us to reach more people through television advertising than we would have without it. As for those who choose to fast-forward through advertising, the ads are retained even if the viewer is fast-forwarding at the fastest rate,” Crawford says.

Ads in the last minute before a show comes back on are best positioned, given a viewer’s habit of pressing play before a commercial break ends. And, says NCC Media’s Kay, the types of programming people watch on cable are different from shows that do well on broadcast. While the average consumer might record a hit primetime show or a sporting event, they are much less likely to record something on the Food Network, which broadcasts hours of the same type of programming.

“It’s not appointment viewing,” says Kay.

DVRs have yet to reach the stage some advertising companies feared they would; Crawford says five years ago, some of those firms believed the DVR would make them obsolete. But habits are hard to break, and consumers still overwhelmingly prefer to view their favorite shows in real time.

But the evolution of technology means more campaigns will begin doing what President Obama’s campaign did in 2008—advertising in non-traditional venues like video games, Hulu and elsewhere. Four years ago, Obama’s campaign had such a large ad budget that they advertised in video games like Madden NFL ‘09 and several others in which users connect to an online service. The campaign was able to target users in 10 swing states, and the ads appeared as signage in sports stadiums.

This year, online advertising is already widespread, thanks to Google’s AdWords program and others, and Romney’s campaign has advertised widely on YouTube. J.B. Poersch, a strategist who ran the Democratic Senatorial Campaign Committee for three cycles, says he expects campaigns to reserve more than 10 percent of their overall budgets for other social and nontraditional media efforts.

Party strategists on both sides are taking more care with their advertising money, even as the amount of money available to a campaign balloons. Finding the right programs and the right persuadable viewers within the right window may make the difference between a win or a loss—and, with the Senate so narrowly divided and the House potentially in play, it may mean the perfectly-timed surgical strike or the right kind of sustained outreach could wind up determining which party sends a majority to Washington.

Stay tuned for what’s certain to be a long, and crucial, commercial break.

Reid Wilson is editor-in-chief of National Journal Hotline.