WASHINGTON — Happy anniversary, Citizens United. Here’s an email — or two or three — from Sen. Al Franken to mark the occasion.

Franken, a vocal critic of the four-year-old Supreme Court decision, sent his supporters a fundraising appeal this morning (“Thanks for helping me wish Citizens United a terrible birthday,” he wrote). Later, he asked them to support an anti-Citizens United resolution at February’s precinct caucuses. Then Sen. Amy Klobuchar chipped in, sending a Citizens United-themed fundraising request on Franken’s behalf to her email list (Franken was asking for $50,000 in donations; Klobuchar set a more ambitious goal of $100,000).

Franken — up for re-election this fall — has long opposed the Supreme Court’s decision in the case, which opened the door to unlimited campaign spending from corporations and labor unions and precipitated the rise of super PACs. Last year, he helped introduce a bill that would have forced political organizations to disclose the identities of their biggest donors, but the bill failed twice on the Senate floor.

(While we’re talking about campaign finance, here’s something to watch: the Supreme Court heard a challenge to federal limits on individual campaign donations last fall. A decision in that case — McCutcheon v. FEC — could come any time.)

Anyone on a Democratic emailing list may have noticed the occasional reference to the Koch brothers or Karl Rove in fundraising pitches so far this cycle. Both ran massive Republican super PACs in 2012, and are apparently effective enough boogeymen for Democratic donors to warren a mention in fundraising emails.

They got one in Franken’s note today: “Maybe it might motivate you to imagine Karl Rove and the Koch brothers wearing party hats and frowns because our Day of Action ruined their Citizens United party? I thought so.”

Devin Henry can be reached at dhenry@minnpost.com.