Israeli politicians often complain about the power of the media and its pervasive influence. But in recent weeks, some of them have put themselves at the disposal of the local press barons in an attempt to block the new competitor in town.

A number of MKs from various parties are trying to gather a majority for a new law that will forbid foreign ownership of national newspapers. Though his name appears nowhere in the draft proposal, the target of the law is very clear: casino mogul and mega-philanthropist Sheldon Adelson, the richest Jew in the world and a self-professed “very right-wing” Zionist.

In the two-and-a-half years since it first appeared, Yisrael HaYom, a daily tabloid founded with Mr Adelson’s money, has swiftly become the country’s second most popular newspaper.

There is no secret to its sudden success. Yisrael HaYom is free and distributed throughout much of the country in corner shops, cafes, in train stations, to drivers at stopping lights and to private homes in selected areas.

But Yisrael HaYom is like no other Metro-syle freesheet. It is heavy on editorial content, has signed up some of Israel’s better known reporters and celebrities as writers, and has a clear editorial agenda.

Mr Adelson and his family are close to Prime Minister and Likud leader Binyamin Netanyahu, and for many years he has been an influential donor to the Republican Party in America. From the moment his paper hit the stands, it was a fierce critic of the Olmert government, backing Mr Netanyahu’s Likud into the elections and subsequently his government following Likud’s victory.

The paper also includes columnists critical of the government. But the broad direction is unquestionable and has caused some critics to describe it as a “Bibi-ton”, an accusation that Adleson recently denied in a rare interview with the Jewish Telegraphic Agency.

He simply wanted to offer Israelis “fair and balanced” news coverage, he said. But the attempt now to raise legal barriers to the paper’s existence has little to do with its political positions and everything to do with the financial trouble it is causing Israel’s national tabloids, Yediot Ahronot and Maariv.

Maariv’s publisher and part-owner, Opher Nimrodi, has even been to the Knesset recently, trying to persuade legislators to support the new law.

Both the tabloids feel under threat. Maariv, which was the second most popular paper in Israel before Yisrael HaYom appeared, has been haemorrhaging money for years. In 2008, the paper lost NIS 132 million. Losses this year are expected to be around NIS 70 million, but the improvement was largely due to deep cutbacks and an asset sale.

Industry surveys have placed Yisrael HaYom as the clear number two in terms of circulation and exposure. This has cut into Maariv’s sales and into its advertising revenue.

Yisrael HaYom did not initially seem to pose a threat to Yediot Ahronot, by far the most widely read paper in Israel for over 30 years. Yediot’s predominance was seen as too entrenched to be uprooted by the freesheet. But the paper’s owners, the Mozes Family, became concerned when it emerged that Yisrael HaYom, which for its first two years had appeared from Sunday to Thursday, was planning to add a Friday edition, including weekend magazines.

Unlike Maariv, Yediot is not a publicly quoted company and does not publish financial reports. But it is widely known that the paper makes its main advertising revenues from the Friday magazines, a million of which are rumoured to be distributed in a country where the entire Hebrew-speaking newspaper-reading population is around four million.

Yediot fears Yisrael HaYom’s Friday issue, now distributed in 250,000 copies, will force it to cut the high fees it charges for full-page colour ads in its magazines.

It is still unclear how many MKs may support the new law. Many, especially Likud members, are torn between political loyalties, a notional belief in freedom of the press and their fear of the power of the tabloids, especially Yediot Ahronot, to make or break a political career.

It is a power the papers’ owners are loath to relinquish.