Mayor Nutter joined the growing chorus of people calling on GOP presidential candidate Mitt Romney to release his tax returns.

Here's a bit from a letter he and 20 other mayors signed and release Thursday:

"Your own father set a precedent for presidential candidates, of both parties, when he said public release of several years of tax returns was necessary, explaining that "one year could be a fluke, perhaps done for show."  President Obama has released 12 years of tax returns, John Kerry released 20 years' worth and Bob Dole released nearly 30 years.  Without releasing additional tax returns, you would go down as one of the most secretive presidential nominees in modern history.  Even Richard Nixon released more years of tax returns than you."

Nothing surprising about Nutter, a Democrat, going after the Republican candidate in an election year.

But it was a little unusual that he did so just moments after leaving a press conference where, as president of the U.S. Conference of Mayors, Nutter called on Congress and the next president - whether it is Obama or Romney - to boost infrastructure spending to boost urban economic growth.

The Conference is nonpartisan, after all. Nutter said he was merely saying that Romney should release his financial information, just as Obama has done. The mayor also noted that some prominent Republicans have even called for Romney to release his returns.

But even during the transportation spending press conference, political talk seemed unavoidable. Michael Coleman introduced himself as mayor of Columbus, "swing state" Ohio. That prompted Baltimore Mayor Stephanie Rawlings-Blake to say she was from "safe" Maryland.

And when some of the mayors said they really wanted to meet with House Speaker John Boehner about finding money to invest in the country's roads and bridges, Akron Mayor Donald Plusquellic volunteered that the Speaker "treats us all like crap."

Later, Plusquellic said he'd had a good working relationship with Boehner when he was a politician in Ohio. But that has changed since Boehner became Speaker of the House, Plusquellic said. The U.S. Mayors have traditionally met with every Speaker, but Boehner won't sit down with them, Plusquellic said.

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