They predicted beforehand that the Feb. 17, 2013 Forward on Climate Rally at the Washington Monument would be "the largest climate rally in history," then afterward claimed "nearly 50,000" showed up.

Optimistic crowd estimates from rally organizers are nothing new in this town, so it was no surprise that on the same day a Washington Post reporter put the attendance at 35,000.

At first glance, it might appear that reporter Steve Mufson was doing what journalists are supposed to do, which is to cast a critical eye on things like crowd size estimates from rally organizers of all political stripes.

It turned out, however, that Mufson's figure came from rally organizers, and the rest of his report on the day's events was equally uncritical. Particularly noticeable for its absence from the story was information on who paid for the rally.

The New York Times' sustainability writer, Christopher F. Schuetze, at least pointed out in his last paragraph the fact that the organizers claimed two different estimates for the crowd size. But nothing about the event's funders.

Why such reportorial apathy about the funding behind Forward on Climate? Both the Post and the Times have a demonstrable record of obsessing about things like the Koch Brothers (i.e. conservative, typically Republican-related), and virtually zero interest in looking at who pays the freight for groups on the Left, like the organizers of the Feb. 17 demonstration.

Since this is Sunshine Week, here's the reporting left undone by the Post and Times concerning who paid the freight for Forward on Climate, as researched by Washington Examiner columnist Ron Arnold, an expert on the incredible amounts of money that lubricate the Big Green political machine.

Here's what he found: The group was founded in 2007 and took in $3 million in 2011, of which $371,300 came from seven foundation grants, according to the organization's most recent IRS 990 tax return.

One of those grants, the Overbrook Foundation's $80,000 "gift," specified that it be used for the "Keystone XL campaign."

The Sierra Club also pitched in. It has received 1,831 grants all-time, worth a cumulative $292.7 million, including $3.4 million from the Tides Foundation, which specializes in connecting anonymous donors with progressive (i.e. liberal, typically Democrat-related) causes. Tides has pumped five times as much money into its favored political outlets as the Koch Brothers have into theirs.

A look at some of the other groups participating in the Feb. 17 rally shows a lot more of the same sort of supposedly nonpolitical philanthropic funding for "progressive" causes.

The Minnesota-based Indigenous Environmental Network, for example, got 62 grants totaling $1.7 million. Twenty-three of those grants came through the Tides Foundation.

The Energy Action Coalition's "youth climate movement" was funded via 35 all-time grants totaling $2.2 million. This coalition is a project of the Earth Island Institute, to which 772 all-time grants have been awarded worth a total of $28.3 million.

Other groups participating in the rally include the Rainforest Action Network (402 grants, $11.2 million), Chesapeake Climate Action Network (80 grants, $2.7 million), Oil Change International (29 grants, $1.3 million) and Labor Network for Sustainability (4 grants, all from the Tides Foundation, $110,000).

The problem here isn't the funding -- philanthropists should be able to fund whatever suits them, no matter how wacky it might be. The problem is the double standard in the mainstream media's reporting and commentary on "money in politics."

Why do these folks get so bent out of shape about the Koch Brothers, but they can't be bothered to look at the other side? Could it be they're afraid they will discover that the really big money in American politics is on the Left, not the Right?

Mark Tapscott is executive editor of The Washington Examiner.