A group of progressive U.S. senators have fired their second shot in a war against the First Amendment.

The group, led by Democrats Harry Reid, Bernie Sanders, Elizabeth Warren and Al Franken signed a letter suggesting the Idaho Freedom Foundation and its free-market allies release their donor information.

The letter was distributed after IFF and other sister organizations protested a coordinated, Democratic-led attack on those who speak out against global warming. Click here to read IFF’s response to Democrats’ intimidation tactics.

Idaho Freedom Foundation Vice President Fred Birnbaum responded Tuesday to the Democrats’ war on free speech and free association:

It is no surprise these progressive senators would conflate the debate on climate change with a discussion of those who donate to our organizations. The reality: those who have publicly called into question elements of the climate change story have faced personal and professional threats. So when these progressives say, "we would just like to know whom it is we are debating," what they are really stating is that they would just like to know who they can intimidate with the full police power of the federal government. If the debate on climate change in the public arena represents the future of open discussion then the notion of free speech as embodied by the First Amendment is in serious peril.

The Idaho Freedom Foundation stands with its allies as we face attacks from those who seek to use the platform and machinery of government to harass and intimidate.

Please stand with us. Donate $50 today to help IFF fight Bernie Sanders, Harry Reid and Elizabeth Warren. IFF’s policy is to protect the privacy of its donors, and we will stand by that promise.