Candidates and interest groups poured a mind-boggling $2 billion into television advertising in the previous election cycle, but political consultants are asking whether that is money well spent.

Numerous ad-makers complained that their spots did not penetrate voters’ consciousness because of the cluttered airwaves. In such an environment, strategists are rethinking the role of traditional campaign commercials.

“Because of the clutter on TV, voters are more skeptical now,” said John Brabender of the GOP media firm Brabender Cox. “Ads are not having the same impact across the board.”

Politicians have always had to fight alongside soap and car commercial to get Americans to listen. But now, television viewers are finding more ways to bypass commercials altogether.

The old political industry standard was to buy 300 points of advertising, which theoretically assured that everyone in a particular market would see an ad three times, during local TV newscasts.

Since the 1980s, that number has jumped to 1,000 points.

Now campaigns have to buy more rotations and work harder to target specific demographics, media consultants agree — for example, buying 1,000 points during “Oprah” to reach married women.

“There’s no question that voters are bombarded with more information than ever before and campaigns need to continue to search for more effective ways to reach them,” said Erik Potholm, a partner with the GOP media firm Stevens Reed Curcio & Potholm. “Cable is becoming a more and more effective tool as well, especially when you go beyond the traditional news channels to more highly targeted networks that index high among key voter groups,” he said, using the Food Network or Travel Channel as examples.

Many GOP consultants said that the political environment for Republican candidates was so negative last year that even buys of 1,500 points and more were not very effective.

“I think 2006 was a bit of an aberration … and commercials probably mattered less,” said Brabender, whose clients in the previous cycle included former Sen. Rick Santorum (R-Pa.).

Curcio said cycles of hyper-activity require even bigger ad buys.

“When TV markets are overcrowded, as they were in so many key markets in 2006, campaigns need to significantly increase the number of points they run behind a message in order to penetrate,” he said. “If they don’t, their message will just get lost.”

But GOP pollster David Winston of The Winston Group said candidates are facing another hurdle that is getting higher every year. Cable TV news is seeing its audience grow. Given the pressure to deliver information around-the-clock, the cable networks often feature the same news on any given day, Winston said.

“There are five or six national, political storylines going on at any time,” he said. “And if your campaign isn’t tying into those, it is going to be very difficult to fight through the clutter.”

Finding ways to change the subject, so to speak, will only get harder for politicians, Winston said.

“Too often people think ‘just run more ads’ when I think often the solution is to make more creative and interesting ads,” Brabender said.

All the consultants agreed that buzz-generating ads are effective.

Using ads to get “earned media” — making a commercial that becomes newsworthy — can reap huge benefits if a relatively small buy grabs headlines, such as the Swift Boat Veterans for Truth commercials did during the 2004 presidential campaign.

Campaigns had mixed success with that technique last year.

Actor Michael J. Fox starred in commercials for now-Democratic Sens. Claire McCaskill (Mo.) and Benjamin Cardin (Md.) to promote their advocacy of stem-cell research.

While celebrities entering the political fray has become commonplace, the commercials quickly became news as conservative radio host Rush Limbaugh stoked controversy by accusing Fox of ditching his Parkinson’s medication to seem more sympathetic. The backlash Limbaugh’s comments caused helped McCaskill topple former Sen. Jim Talent (R-Mo.).

Conversely, tried-and-true attack ads sometimes backfired, even if they made news.

During the race to replace retiring Rep. Sherwood Boehlert in the Empire State’s 24th district, the National Republican Congressional Committee blasted now-Rep. Michael Arcuri (D-N.Y.) of using public money to call a sex-phone service. The NRCC’s humorous, racy ad did not mention that the call was apparently made in error and lasted less than a minute.

Many ad makers employ humor to make their work stand out. While the technique often succeeds — think of 1992 spots for Sen. Russ Feingold (D-Wis.) — one person’s friendly ribbing is another’s insult.

Now-Sen. Bob Corker (R-Tenn.) nearly lost the seat vacated by former Senate Majority Leader Bill Frist (R-Tenn.) last year when the Republican National Committee produced an ad that starred a scantily-clad white woman who implored then-Rep. Harold Ford Jr. (D-Tenn.) to “call her,” Republican operatives privately agree. The poke at Ford’s reputation as a “player” struck many experts and viewers as racism masked as humor.

TV ads will continue to matter but media experts advise candidates gearing up for 2008 and beyond to look at other media.

“You’ll be seeing a lot of people moving dollars to new media,” Brabender said. “TV certainly is very powerful and very relevant but I think it needs to be integrated into a full media strategy … Web, mail, earned media.”

“Candidates who rely solely on TV do so at their peril,” he added.

While no one disputes that using emerging technology such as Web casts, downloads to iPods and more narrowly casted messaging is the future of campaigns, media consultants say TV will continue to dominate for now.

“TV ads are like the compulsory event of the ice skating competition,” said Democratic strategist David Dixon of Dixon/Davis Media Group. “If you don’t have them, you’re not getting to the free skate.

“Will you win on your ads alone?” he asked. “Maybe not, but you are not gonna be competitive without them.”

David M. Drucker contributed to this report.