Local TV stations will see a flurry of political advertising in the next month-and-a-half as the Democratic candidates for president blanket the airwaves with ads.

"We expect significant candidate and political advertising," WTAE general manager Rick Henry said. In the days before Tuesday's voting in Ohio, Texas, Rhode Island and Vermont, representatives from the campaigns of Sens. Hillary Rodham Clinton and Barack Obama contacted Channel 4's sales department.

Rates for 30-second TV spots vary by time period and station, but one political ad in an 11 p.m. Pittsburgh newscast -- the most expensive newscast of the day for advertisers -- can cost between $1,250 and $1,800.

At KDKA, the only advance call came from representatives of Sen. John McCain, who has secured the Republican nomination.

"They haven't placed any [ads], and given [Tuesday's] results, I don't know that they will," KDKA general manager Chris Pike said.

WPXI general manager Ray Carter said his station received inquiries from both the Obama and Clinton camps before noon Wednesday.

In recent campaigns, political ads have aired primarily during newscasts, but this campaign is not traditional.

Both campaigns bought time on Sinclair's Fox and My Network TV stations in San Antonio, said Alan Frank, a Sinclair group manager who oversees Sinclair-owned stations in Buffalo, N.Y., San Antonio and Charleston, W.Va. The campaigns also have been more willing to buy ads outside of news during sitcom reruns in "access" -- the hour before the start of prime time -- and late-night, when younger viewers are more likely to be watching.

"The good news for a Fox group is they're looking for younger viewers or the younger voter," said Mr. Frank, who also is general manager of local Fox affiliate WPGH and MNT affiliate WPMY. "Hopefully we'll do better than we've done in the past."

Trade publication Multichannel News found experts predicting political spending on TV ads could add up to as much as $2.5 billion this year.

TV Week reported that between them, Mrs. Clinton and Mr. Obama spent $12.6 million on advertising in Ohio and Texas in just the first two weeks of the three-week run-up to the Tuesday primaries. Mr. Obama, in particular, also has directed expenditures to ads on the Internet.

It's not just broadcast channels that benefit. Bill West, political specialist for Comcast Spotlight, which sells national and local ads on cable in Pittsburgh, said he had a speculative contact from Mr. Obama's ad reps two weeks ago.

"I wouldn't be surprised to see some level [of advertising] to start fairly soon," Mr. West said. "Both campaigns recognize now it's a new game, regardless of how anyone wants to tout the score. Both candidates appear to be in this for the long haul."

Radio stands to benefit from candidates' spending, too. "Obama for President" was the leading radio advertiser among political campaigns for the week of Feb. 25-March 2, according to Media Monitors, airing 15,748 spots nationwide. Mrs. Clinton's campaign was second with 3,074 spots aired as Tuesday's Texas and Ohio Democratic primaries drew near. Radio Ink Magazine reports that Mr. McCain ran 181 radio spots nationwide during the same week.

Dennis Wharton, executive vice president of the National Association of Broadcasters, said, "Generally, political advertising goes into talk formats. Those are folks who more often than not are voters."

But he added that this election is unusual in that youth turnout is a key issue, so music formats could also come into play.

Michael Young, KDKA senior vice president and general manager, said Wednesday that it's too early to start seeing much advertising, but, like Mr. West, he expects it's coming "fairly soon."

"These are two candidates who really want to get good voter turnout," he said.