In a move whose sole surprise was its timing, journalist Yair Lapid stepped down Sunday from anchoring the popular Channel 2 news magazine, Ulpan Shishi, and said he was planning to enter politics.

The resignation was immediate; and as of Sunday night, it wasn't clear who would be hosting this Friday's edition.

Lapid, 48, a best-selling author, talk-show host and Yedioth Ahronoth columnist who has anchored the top-rated weekend news program since 2008, is expected to start a new political party rather than join an existing one.

Recent polls have shown that a party headed by Lapid would do well, particularly with secular voters, and could earn between 15-20 seats. It is thought that most of those seats would come at the expense of the Kadima party, though Lapid could also draw votes from the Likud and Yisrael Beiteinu.

While the next general elections are set for October 2013, analysts believe elections could take place as early as this year.

Lapid had long hinted that he was considering a political career, but had said he would make that decision much closer to election time. He was apparently motivated to take this step now by efforts to pass a bill dubbed "the Lapid law," which would set a six-month cooling-off period for journalists seeking to enter politics.

In a statement he issued on Sunday, Lapid specifically referred to the bill, saying he hoped his resignation from Ulpan Shishi would "stop the legislation of the embarrassing and anti-democratic bill to cool off journalists."

He later wrote on his Facebook page, which as of last night had over 31,400 followers, that he was "embarking on a new path.

"I am equipped with the power of knowing I am doing something I believe in. You are my community and I draw my strength from you. I promise to post updates here and to continue to listen to you," he wrote.

Lapid is the son of the late Yosef Lapid, who was also a journalist who crossed the line into politics, boosting the popularity of the moribund Shinui party when he joined it in the late 1990s.

As party chairman, he led the party to six seats in 1999, and then 15 seats in 2003, when he joined the government led by Ariel Sharon and became justice minister.

Speculation was rife on Sunday about who else might join a Lapid-led party to run for Knesset. Among those touted are Herzliya Mayor Yael German, who told a local paper in the past that she would join Lapid if he pursued politics.

Karnit Goldwasser, the widow of the kidnapped and slain soldier Ehud Goldwasser, is also considered a candidate. Neither German nor Goldwasser would comment.

Another journalist, Ofer Shelah, is also being mooted as someone who would bring to such a party the weight of his experience covering security and defense issues. Shelah could not be reached for comment.

Another possible candidate is Rabbi Shai Piron, who heads the Petah Tikva hesder yeshiva, though he said on Sunday that he had no plans to enter politics.

Lapid had long toyed with the idea of a political career. In an interview six years ago, for example, he said that if he were a true man of conscience, he would go into politics. In an interview with Haaretz three years ago, he said he was debating the move "and would continue to debate it for a long time.

"Sometimes it seems to me that it's not just me, but everyone of my generation, who, because they've been coddled, decided that politics is not our business, and this has caused a problematic situation... Now, I think that people have to do things that have an influence on society," he said.

Over the past year, rumors of his pending pursuit of politics strengthened as he periodically dealt with political and public affairs in his columns; though when asked if his move was imminent, he would deny it. The rumors started anew in late summer, when he published a "social covenant" in his column and on his Facebook page.

In every one of the hundreds of talk shows he hosted over the years, he would ask his guests the same question, which eventually became his trademark: "What do you consider truly Israeli?"

He received many answers, and when he asked his father the question, the latter looked at his son emotionally and said, "You are."

Lapid's obsession with Israelis and Israeliness had become one of the focal points of his columns in recent years. He has positioned himself as the typical "modern Israeli" and is always seeking to define the various facets of contemporary Israeliness.

Though he vehemently opposed any effort to pass laws that restrained journalists, at a press conference called by fellow journalists in November to protest them, he said, "I believe that the leftist [media] guild is in no small measure responsible for them."