Philadelphia Finance Director Rob Dubow was a bit more politic than his boss, but his message Tuesday was the same: The plans offered by the Democratic mayoral candidates to fund city schools just don't add up.

"It is not like these are all horrible ideas," Dubow told a room of reporters. "It is, they just don't get the district what it needs."

That was a more measured assessment than one offered last week by Mayor Nutter, who called the candidates' solutions to the school funding crisis "bogus."

"Let's cut the phoniness," Nutter said. "Let's be serious about educating kids."

Nutter has offered his own proposal - a 9.4 percent property-tax increase - which, not surprisingly, has been uniformly snubbed by the six candidates facing voters in the May 19 Democratic primary.

Rather than promising voters a tax hike, the candidates have offered up a pastiche of easy-sounding solutions to painlessly raise $105 million for the School District.

Nutter, along with multiple public commentators, has suggested those "solutions" represent little more than a ruse to avoid voter backlash.

Dubow, at the mayor's urging, dissected the proposals, contending that they, variously, would take forever to come to pass, raise far less money than needed, represent a one-time payment, or drain funds now going to city services.

For instance, State Sen. Anthony Hardy Williams has proposed shifting a greater percentage of the city's property taxes to the School District. Dubow acknowledged that such a change could raise $54 million for the schools immediately. The downside: That money would have to come from funds now going to the city's operating budget, meaning services would have to be cut.

Another solution favored by virtually the entire field of candidates is to raise commercial real estate rates. Dubow said that would require a change in the state constitution, which could take several years - if it passed at all. And it would require a 23 percent increase to raise $105 million for the district.

A plan offered by Nelson A. Diaz and Doug Oliver would extend bar closings in Center City from 2 to 4 a.m. In theory, more alcohol would be consumed, raising funds through the city's 10 percent drink tax. Dubow dismissed the boost as inconsequential. He also noted that the change would need state approval.

One element of James F. Kenney's proposal calls for selling liens on back commercial real estate taxes. Dubow estimated that would bring in less than $30 million and would be a one-time windfall. He did add, however, that it was an idea the administration was considering.

Oliver has proposed negotiating deals with the city's largest tax-exempt nonprofits - such as universities and hospitals - to extract contributions for schools. Dubow said such agreements would likely yield less than $10 million.

He said the city could expect even less return on a plan offered by Diaz to change the manner in which the city manages its pension funds.

All of which was a long way to come back to the mayor's own plan.

"We look at the other options," Dubow said, "and this was the only one that met the criteria we needed - stable, recurring funding that started right away and would not damage city services."