With Maine one of 17 battleground states in which the two presidential campaigns are saturating local advertising markets, voters here can’t help but take notice.

Thus far, political scholars are marveling at the sheer number of ads, the latest of which began airing this week as part of an $18 million buy by presumptive Democratic nominee U.S. Sen. John Kerry of Massachusetts.

“We’re seeing if not the earliest advertising, the most intense advertising barrage to date, and certainly a lot of them are negative,” said Ken Goldstein, a University of Wisconsin at Madison political scientist and noted nonpartisan expert on the subject.

Much of the early negativity would appear to have come from President Bush, more than 75 percent of whose ads have been attacks on Kerry, according to a Washington Post analysis. For comparison, just 27 percent of Kerry’s ads have been negative.

Those numbers, however, don’t tell the whole story, warned Goldstein, noting significant negative ad buys on Kerry’s behalf by nonprofit groups critical of Bush policies.

“Has Bush been very, very negative? Yes,” Goldstein said. “But add in MoveOn.org and the Media Fund, and Bush and Kerry would look virtually identical.”

But Jesse Derris, Kerry’s campaign spokesman in Maine, was quick to limit the comparison to messages disseminated and approved by the candidates themselves.

“The president is responsible for what his campaign produces, and what they’re producing are lies,” Derris said. “Our voice is positive. Their voice is negative and John Kerry’s positive vision for Maine and American will drive voters to our campaign.”

Bush campaign officials on Thursday rejected the negative label.

“We are comparing and contrasting very different records of accomplishments and two very different visions,” Bush campaign spokesman Kevin Madden said, contending that Kerry most often has used his stump speeches to distort the president’s record. “It’s not all about the advertising.”

Campaign watchers nevertheless have saved most of their criticisms for the president, whose latest ad contains several distortions of Kerry’s position on the USA Patriot Act, according to the nonpartisan Annenberg Public Policy Center.

The ad, which accuses Kerry of “playing politics with national security,” falsely claims the Democrat would repeal the act’s expanded wire tapping, subpoena and surveillance powers, the center concluded on its Web site, FactCheck.org.

Instead, Kerry has said he would change the law to require more oversight of the practices.

Meanwhile, Kerry’s comparatively positive messages of late appear to be paying dividends in the battleground states, based on an Annenberg survey released last week.

The report found that Kerry’s favorable ratings improved eight points to 44 percent in those states. Bush’s declined four points to 44 percent. In states where the ads weren’t running, there was no change.

In Maine, Yasmin Boyorak, a 47-year-old retail manager from Bangor, has been watching the ads closely. She issued a warning for any candidate who used too much television time to tear down an opponent.

“Pretty much I turn it off when they start that,” said Boyorak, who is not enrolled in a political party. “If you can’t convince me to vote for you on your merits, don’t even bother.”