Bypassed by those who doled out cash for the presidential and statewide campaigns, radio station operators will head to Sacramento this month to lobby for more political ad dollars.

The Southern California Broadcasters Association is leading a group that will try to convince political advertisers, campaign consultants and media strategists about the effectiveness of the medium.

“We have seen TV get the lion’s share of political advertising for propositions and referendums while we were left with the scraps,” said John Davison, general manager of Walt Disney Co.’s four-station L.A. cluster and chairman of the association. “We wanted to proactively go after the political ad money well in advance of the next state elections.”

In particular, the association is seeking money from propositions because, unlike individual campaigns for political office, California doesn’t limit contributions to issue-oriented campaigns populating each ballot.

Mary Beth Garber, the association’s president, conceded that the effort would be difficult because of the fragmented nature of the radio audience. “These people only believe in television,” she said. “They’re interested in beating people over the head over and over again with TV ads, until people don’t want to watch TV anymore.”

Roy Behr, a partner at GMMB Inc., an L.A. political advertising firm that devises ballot initiative strategies, said there is no substitute for television when it comes to reaching larger audiences and communicating emotional messages. “The largest radio ratings at any time may be 1 or 2 percent of the audience,” he said, “but with TV, you can still reach double-digits in prime time.”

Moreover, advertising ballot initiatives on television has a particular advantage over radio because a TV ad can show the proposition’s number on screen continuously. On radio, he said, every time a proposition number is repeated it takes up more time that otherwise would be devoted to the message.

Where radio advocates tout audience fragmentation is in the ability to address a message to a particular demographic. Calls to vote for or against an initiative of particular interest to one group can be targeted to Christian rock or Hispanic radio stations.

The broadcasters association points out that in 2004 the Bush campaign spent 75 percent of its advertising money on TV and pumped the rest into radio and cable, compared with 95 percent on television four years earlier. The switch to more radio and cable reflected research showing more Democrats watch mainstream TV than Republicans.

Radio industry lobbyists also will cite the campaign to oppose Proposition 66, which would have curtailed the state’s three-strikes law. Backed with a $2.5 million contribution from Henry Nicholas III, founder and former chairman of Broadcom Corp., the campaign spent heavily on radio in the last days of the race. The measure was defeated, with 52.7 percent of the vote.

While radio executives point to the success of the effort, radio was not the first choice. The inventory of TV ad time was scarce and expensive the weekend before the election, prompting the “No” campaign to blanket the state, especially Los Angeles, with about $2.5 million worth of ads on more than 100 radio stations the weekend before the election.

Just after the election, the broadcasters association’s executive committee, consisting of heads of L.A. radio clusters from Clear Channel Communications Inc., Univision Communications Inc., ABC Radio Networks, Infinity Broadcasting Corp., and Emmis Communications Corp., invited Nicholas to speak at their Dec. 3 board meeting about the effectiveness of his radio ads.

Ray McNally, president and creative director of McNally Temple Associates Inc., a Sacramento political advertising firm that orchestrated the campaign, downplayed the role the radio ads played.

“The governor did a news conference in Southern California Oct. 20,” McNally said. “We put our TV spot on Oct. 25 in L.A. The governor ran his two TV ads Oct. 27. Obviously, radio helped, but the primary message carrier in any statewide campaign is television. The Field Research poll showed Prop. 66 was starting to nose-dive by Oct. 23.”