San Francisco politics—a mix of the very good and the very ugly— are usually a bell weather for only one city—San Francisco.

There is no plain “bad.” This is a city of extremes.

If Trump ever gets his great wall, it will bear no comparison to the two great bridges in the City by the Bay.

Oher cities experience racial riots that get out of control. San Francisco welcomes vocal protestors at its public meetings.

Marathons featuring racers with exotic clothing or no clothes at all is standard fare.

And Mayoral successions with the exception of the dark interlude following the assassination of Mayor George Moscone decades ago are even by this city’s permissive standards rather sedate affairs even when radical changes are happening.

That may or may not change as the 2018 Mayoral race gets underway.

 But much of the state and the nation will be watching after the premature death of the highly likeable and its first Chinese-American Mayor, Ed Lee, just over a month ago.

The city is a veritable nursery for churning out winners who have gone on to make a national splash.

Lt. Governor and now gubernatorial hopeful, Gavin Newsom launched his meteoric rise as the Mayor and there are those who claim his aspirations may go much higher than the statehouse.

Sen. Dianne Feinstein, another former Mayor, is making headlines as a crusading investigator and ranking member of the Senate Judiciary Committee where some of the revelations about the Russian connections could result in the ultimate undoing of the president.

The latest cast of City Hall wannabees includes a well-known former State Senator—Mark Leno—who would become the first gay Mayor; Jane Kim, a combative Supervisor who would be the first Korean to hold the office; and the current Board President and savvy pol, London Breed who is African-American.

Joining this trio is Angela Alioto whose father, Joe Alioto, reigned in the 1960s and a former far-Left Supervisor who has been out of the limelight for many years while acquiring some continuing fame as a criminal defense attorney.

All are Democrats in a city where Republicans are pretty much extinct.

In the early going the front runner is the undecideds and there is no natural successor to Lee whose policies came to define a city struggling to find common ground pitting forces that advocate rapid downtown development led by an invasion of hi-tech companies against others being pushed out by skyrocketing real estate costs and further urbanization.

San Francisco boasts the priciest real estate in the nation with the medium value of a single family home at $1.3 million and the median rents topping off at $4,400.

This has led to an explosion of high-paying jobs fueled by generous tax favors for enterprising companies such as Twitter which has set up headquarters, and Salesforce which erected a 1070 foot behemoth towering over everything else and now the tallest building on the West Coast.

When the battle lines come into full view they will feature Big Business interests and the construction unions who are feasting on the new prosperity and calls from neighborhood activists opposing changes that threaten to redraw the city’s landscape.

The old guard, anchored by the re-doubtable ex-Mayor, lobbyist, all-time kingmaker and S.F. Chronicle columnist, Willie L. Brown, still has plenty of gas in the engine and will be working hard to get Breed elected.

Brown and a few other influential community leaders were responsible for Lee’s rise to power and would prefer someone that would continue to carry out his policies.

Arrayed against it is an emerging group of new-breed lawmakers which leans more strongly to the left, wants to see more affordable housing and bemoans the loss of social equality.

Its nominal leader, Supervisor Aaron Peskin who vanquished an incumbent to regain his seat in a bitter contest last year, has endorsed Leno who generally supports the progressive agenda, and would prefer appointment of an “interim” caretaker Mayor until the voters make up their minds in the June election.

That will have to get sorted out by the eleven member Board of Supervisors which is unlikely to cobble together the six votes needed to appoint one of its own and they cannot vote for themselves.

Breed will thus have to surrender her Mayoral title and the higher name recognition that comes with incumbency.

This will set the stage for a bruising contest in a city that relishes such combat and is the frequent target of controversy.

But the big fights are generally waged over differences about how much money should be spent on sprucing up county jails vs. more daycare centers or the best methods for attacking homelessness which no previous Mayor has been able to solve.

When it comes to broad social issues, the majority of its lawmakers are generally in lock-step agreement. That’s likely to be the case in this election go-around.

San Francisco led the nation when it granted same sex marriages long before the Supreme Court declared them constitutional and is currently drawing wrath from Attorney General, Jeff Sessions, for offering sanctuary status to immigrants accused of committing crimes.

As in other city’s elections the candidates with the biggest bank rolls always have the edge.

However, in this contest for an open seat with no heavily favored successor another factor comes into play that makes predictions more difficult.

It is called ranked voting—newly adopted several election cycles past—and it resulted in a few surprise wins for candidates less known to the public.

It applies to the Mayoral race where voters rank their preferences in order and there is no winner until someone gets a majority. This puts a premium on a superior get-out-the-vote operation.

Given what is likely to be general consensus on many issues and with a narrower than usual field of strong candidates, the outcome in this race will hinge on personality differences and the best message.

That suggests the gloves will come off early.

If history is any guide it could turn into a real brawl.

(UPDATE: Richie Greenberg, a Republican endorsed by the San Francisco GOP, is also announced for mayor.)