STATE SEN. Mark Leno has represented the Marin/Sonoma 3rd District for only a short time, but might be interested in trading in that seat for the mayor’s job in San Francisco. There are many variables that could get in the way.

More over the flip…

Leno would be eligible to run for a second four-year term in 2012. However, he could be campaigning in different ZIP codes when the district lines are redrawn next year as a result of the decennial census-taking. These will be determined by a newly created nonpartisan commission that stripped the Legislature of this power with passage of Proposition 11.

When that work is done, Leno’s district, which presently includes a portion of San Francisco, could be moved entirely north of the Golden Gate or possibly reoriented south of the city to exclude Marin and Sonoma entirely.

It could also remain unchanged – a result which Leno would prefer – since he received 80 percent of the general election vote after a very contentious primary that ousted former Senator Carole Migden in what is a very safe Democratic district.

Apparently Leno’s interest in City Hall was bolstered by a recent San Francisco Chamber of Commerce survey of nine wannabe candidates which showed him coming in first. Until now fellow state Sen. Leland Yee had been leading in the early polls.

When asked how serious these ambitions are, Leno responded, “It is way off in the future and I love representing the people in Marin and Sonoma.”

Any plans he may have will be further complicated by several possible scenarios all of which involve Mayor Gavin Newsom’s decision to run for lieutenant governor.

Were Newsom to win in the primary, and then in November beat the sitting lieutenant governor, most likely Republican Sen. Abe Maldonado, assuming the Assembly confirms him, an interim mayor would have to be either appointed or elected to serve out the year remaining in Newsom’s term.

The guessing game is in full swing as to who that might be with the incumbent thereby getting a strong handle up in the next election.

Former Mayor Willie Brown is mentioned as the safest choice since he cannot run for another term. Another alternative might be the appointment of Board President David Chiu, as acting mayor providing he could muster six votes besides his own.

The principal beneficiary of a Leno Administration would be San Rafael Assemblyman Jared Huffman, who is termed out in 2012 and will no doubt be eying the state Senate.

But were Leno to lose his bid for mayor, since he does not have to surrender his seat to run, he could face Huffman who he would consider his strongest opponent in a re-election race.

The last piece of this musical chairs puzzle revolves around Rep. Lynn Woolsey’s plans. Were she to decide to retire, that seat would be an immediate prize with both Huffman and Leno potential contenders.

For now, Leno plans on becoming better known in his district. Although their future paths could tangle, he and Huffman enjoy a close working relationship and are providing North Bay voters with a double punch that is the strongest in years.

In my next column I take a closer look at Leno’s track record and his stances on controversial issues such as Marin Clean Energy (he is strongly in favor), and the state’s fiscal mess.