Campaign-finance records reveal that nearly 57 percent of contributions to Protect Seattle Now, the anti-tunnel referendum campaign, come from just two big donors---Mercury Group partner Bill Broadhead, who served as Mayor Mike McGinn's chief campaign consultant, and investment advisor (and Sightline Institute board member) Chris Troth. Overall, the campaign has raised a total of around $12,000; of that, $7,000 came from Broadhead and Troth.

The referendum would overturn three agreements the city council signed with the state allowing the deep-bore tunnel to move forward.

This afternoon, city council member Mike O'Brien sent out an email urging tunnel opponents to donate to the anti-tunnel cause, saying that Protect Seattle Now "has a donor who will match dollar for dollar up to $5,000 - if we can raise $5,000 by Sunday!" O'Brien has not returned a call and an email about the identity of the unnamed donor. If the group raises $5,000 and gets a matching $5,000 donation from the mystery donor, more than 53 percent of the campaign's funds will have been donated by just three contributors.