There's the Julian calendar, the Gregorian calendar, the Jewish calendar, and the Philadelphia political calendar, a four-year cycle that begins and ends with the mayor's race.

It shows we're now two years and a couple of months from the filing deadline for the 2015 Democratic mayoral primary, which means it's time for mayoral contenders to be making plans, raising money and recruiting allies.

Really?

"This is like running for president of Philadelphia," Democratic strategist Mark Nevins told me last week. "It's never too early to start."

Because of a curiosity of the city's campaign finance law -- the fact that contribution limits are applied on an annual basis, rather than on the election cycle -- it's smart for anybody who knows they want to run to get their core supporters to give to the max before the regular old Gregorian calendar turns over on Dec. 31.

So City Council members Bill Green, Jim Kenney and Blondell Reynolds Brown, as well as City Controller Alan Butkovitz who faces re-election next year, have all planned fundraisers for this month.

None will say they're running for mayor, since the resign-to-run provision of the city charter means they'd have to resign their city office if they become a candidate. But its widely believed that Green, Kenney, and Butkovitz are running for mayor until events convince them it's a bad idea.

City office holders in a straitjacket?

One potential candidate who isn't burdened by the charter requirement is West Philadelphia state Sen. Anthony Williams, who is said to be actively planning a mayoral run.

When I spoke to him last week, he said people were talking to him about it, and he was listening. It's worth remembering that after Williams lost the 2010 gubernatorial primary, he held an event and declared he'd probably run for state auditor general this year, an idea soon forgotten.

Many have argued that the charter requirement that a city official resign before running for another office places Philadelphia candidates at a disadvantage. Williams can continue to collect his pay and run while in office, risking nothing if he loses, just as U.S. Reps. Bob Brady and Chaka Fattah did in 2007.

And, critics say, the restriction inhibits Philadelphia elected leaders from seeking state or federal office, weakening the city's political influence.

(The framers of the charter said they established the requirement because an official running "is in a position to influence unduly and to intimidate employees under his supervision, and because he may neglect his official duties in the interests of his candidacy.")

A charter referendum to remove the requirement was voted down in 2007, and City Councilman David Oh has said he may introduce a bill to try again. I spoke to him last week, and he's not sure whether he'll do it or not.

The super PACs next time?

While there's plenty of buzz among insiders about who will and won't run for mayor next time, there's also a growing conversation about whether we'll see big money funding candidates in circumvention of the city's campaign contribution limits.

The limits first applied in the 2007 mayor's race, and one reason Michael Nutter won is that he realized early on he'd have to work tirelessly and build a broad funding base. Candidates who thought the limits wouldn't apply and were expecting big checks were disappointed.

But that was then.

"I think the longer the rules have been in place, the more time people have had to sort of figure out where there are opportunities, some people might call them loopholes," Nevins said. "And that money is going to flow somewhere."

The truth is that when the city's campaign finance law was passed in 2003, everyone who read it saw the big loophole: while candidates had to observe contribution limits and could have only one committee, there was nothing to prevent other registered political committees from collecting unlimited contributions and spending as much as they want to influence a race.

It could be the committees associated with electricians' union leader John Dougherty, which pumped a small fortune into defeating a council candidate in 2011. Or it could be the three wealthy supporters of Williams who spent $5 million on his gubernatorial campaign.

I asked Williams if he'd formed a committee to collect contributions within the limits of the city's campaign finance law. He said he hadn't, but that others were raising money intended to help him.

Several sources said an early backer of Williams is Marty Weinberg, the lawyer and fundraiser who was a strategist and confidante of former Mayor Frank Rizzo. Weinberg, who ran for mayor himself in 1999, didn't return my call.

We'll check in again as the political calendar advances.