The black-and-white videos are grainy. Sometimes, they flicker. Yet the images are stark and often graphic, appearing to show senior members of a Turkish opposition party in liaisons with women who are not their wives.

The spies did not just rig hidden cameras. They posted taunting screen text, an eerie soundtrack and even an adults-only rating before slapping the intimate footage on the Internet, unleashing a sex scandal that could benefit the government in elections next month.

The slick smear campaign stunned a hardline nationalist party that was struggling for relevance as a self-declared guardian of Islamic values, pure Turkish identity and the sanctity of the family. It forced the resignations of 10 lawmakers in the Nationalist Action Party, which won 14 percent of the vote in the last general election in 2007.

If the party, known by its Turkish acronym MHP, falls below a vote threshold of 10 percent on June 12, it will lose a place in parliament and many of its seats will go to the likely winner, the two-term ruling party of Prime Minister Recep Tayyip Erdogan.

Such an outcome could have a big impact in Turkey, where Erdogan seeks a two-thirds majority in the 550-seat parliament that would let his party replace a military-era constitution with relative ease. The government says it stands for democracy and European-style reforms, but some commentators judge it increasingly averse to consensus or criticism.

The ruling Justice and Development Party, which has Islamic roots, now has 331 seats. The Nationalist Action Party has 72.

The mysterious group behind the videos urged the ouster of the MHP leadership, whose chief, Devlet Bahceli, served as deputy prime minister in a coalition government a decade ago and has shifted the once-extremist party toward the political mainstream.

"If you have at least a little bit of shame, or devotion to the cause, you should all resign, everybody from head to toe in the management, so that this cherished cause will not suffer further because of you," said an on-screen ultimatum. It described each implicated politician as a "scumbag."

On the face of it, the message suggests the work of party insiders, possibly those who prefer a near-mystical, unrelenting nationalism that has lost resonance as Turkey becomes richer and more open. Speculation about the culprits has also turned on supporters of the government, which vehemently denies involvement, and an alleged gang of coup plotters with shadowy links to state agencies.

One prominent MHP member even accused President Barack Obama of orchestrating the scandal. If his logic was not entirely clear, it fit a tradition of conspiracy theories blaming the United States, which has low popularity ratings in Turkey.

Hasan Gerceker, head of the top appeals court, said only that an "organization" was responsible, acknowledging the operation's sophistication.

The videos, many of which have been removed from the Internet by Turkish authorities, show men resembling half a dozen of the politicians with women in nondescript rooms that appear to serve only as the anonymous settings for trysts. In one scene, a man and a woman cuddle, then disrobe briskly at opposite ends of a sofa and walk off-screen, presumably to a bedroom.

Some scenes are preceded by names of the politicians, whose resignations were taken as tacit acknowledgment that they had been caught in the act, as well as brief data on their partners. They allegedly include a 16-year-old girl and a Russian prostitute.

One video shows men identified as lawmakers Metin Cobanoglu and Recai Yildirim with female partners. Yildirim describes a typical right-wing voter, his own constituency, as "someone with no principles, a round hole, goes in any direction," and muses on his relaxed work ethic.

"I wake up whenever I want, at 10 or 12, go to work at 1 p.m., or 3 p.m. Or I do not go at all," he says. "Nobody tells me when I should go to work, or something of that sort. I am the boss of my own job. If I do not go, nothing happens."

The overhead angle of the concealed camera is often askew, creating a discordant effect. It is amplified by doleful, operatic music paired with recorded sex acts. An "18+" stamp is added, a tribute to the morality issues at stake.

Prosecutors are investigating. Turkish law protects an individual's privacy, but also holds lawmakers to ethical standards.

Ruling party lawmakers, who once tried to make adultery illegal, described the scheme as "ugly," but could not resist barbed remarks on the campaign trail. This month, Erdogan made a not-so-subtle reference to "genelev," which literally means "general house" in Turkish but is a common phrase for brothel.

"The women are not their wives, why would that be their privacy?" the prime minister said. "It is not private, it is very, very general. It is a general indecency."


Kumova contributed to this report from Ankara, Turkey.