“There is a growing threat to political speech in America,” warned Senate Republican leader Mitch McConnell in a speech in Washington, DC last week. “Sadly, a growing number of people on the left … appear to have concluded that they can’t win on the merits. So they’ve resorted to bullying and intimidation instead.”

McConnell focused on “an [Obama] administration that has shown an alarming willingness itself to use the powers of government to silence [conservative] groups.” I focus here on the other half of the threat, intimidation and harassment by private groups on the left.

Some people dismiss the threat from outside organizations as beyond the scope of the First Amendment, which applies to actions by government. Indeed, some unsavory intimidation tactics – such as shouting down speakers or strong-arming companies to drop their sponsorship of conservative broadcasters – actually enjoy First Amendment protection. However, the Constitution affords no protection to criminal acts, which the left is increasingly turning to to silence conservatives.

Most importantly from a constitutional perspective, groups on the left are increasingly enlisting the coercive power of government in their intimidation and harassment campaigns. When they do, they threaten the First Amendment’s guarantee that government shall not abridge the freedom of speech.

Sen. McConnell described one of the more blatant examples of such a public-private partnership in intimidation: “White House officials have long participated in a weekly conference call with a left-wing organization in Washington whose stated purpose is to … mount corporate intimidation campaigns aimed at driving [conservative media] voices clear out of the public square.”

McConnell made it clear elsewhere that he was talking about the left-wing group Media Matters and its “thuggish” tactics. This organization has also generated controversy through its anti-Semitic rants and its anti-Christian mission statement filed with the IRS.

Groups on the left are also turning to the judicial branch to harass conservative opponents. Using the techniques of “lawfare,” they file lawsuits which they’re sure to lose, but only after saddling their opponents with expensive, time-consuming litigation. Witness the New York-based Sexual Minorities Uganda (SMUG), which recently filed a federal lawsuit against Pastor Scott Lively, a well-known pro-family writer, on behalf of homosexual activists in Uganda. The charge: a "crime against humanity."

The mentality of lawfare practitioners is illustrated by a Media Matters internal memo suggesting the organization “look into contracting with a major law firm to study any available legal actions that can be taken against Fox News … I imagine this would be difficult but the right law firm is bound to find some legal ground.” In other words, Media Matters couldn’t identify anything that Fox did wrong but hoped the right lawyer could invent something.

Lawfare’s most persistent practitioner is probably Brett Kimberlin, founder of the radical Justice Through Music Project. He has targeted conservative bloggers like Andrew Breitbart, Patterico, Aaron Worthing, and Liberty Chick, in part, by filing over 100 harassment claims against them in various courts.

Kimberlin claims that blogging the truth about his criminal record – which includes 17 years in federal prison for a weeklong bombing spree – constitutes harassment because it results in angry emails from the blogger’s readers. When Kimberlin gets lucky and finds a naive judge, he not only forces the blogger to defend himself in court, but also gets a restraining order against further “harassment.”

In addition to the courts and White House, the left is turning to various agencies in the Obama administration for help in intimidating their opponents. Angered by the American Legislative Exchange Council’s support of "Stand Your Ground" laws, left-wing groups are coordinating a campaign against ALEC, which includes an IRS complaint challenging its tax-exempt status.

These groups have every reason to expect the IRS will give the complaint high priority. After all, as Sen. McConnell noted, “dozens of Tea Party-affiliated groups across the country learned what it was like to draw the attention of the speech police when they received a lengthy questionnaire from the IRS demanding attendance lists, meeting transcripts, and donor information.”

The benefits of having friends on the inside are well illustrated by a freedom of information request filed with the FCC by Citizens for Responsibility and Ethics in Washington (CREW), an organization handsomely funded by left-wing billionaire George Soros. CREW requested a pile of documents concerning Rupert Murdoch's News Corp., which includes Fox News. The FCC, otherwise known for responding slowly and withholding many documents under exemptions for privacy and the like, delivered CREW’s documents in less than a month.

CREW is also urging the friendly FCC to revoke 27 broadcast licenses held by News Corp’s FOX Broadcasting Company. CREW cites phone hacking by News Corp in Britain, which didn’t involve FOX Broadcasting. Of course, CREW’s real concern is not ethics abroad, but ideology at home.

Not content to harass Fox by using only one branch of government, CREW and its allies also sent a letter to Congressional committees demanding hearings on revocation of the licenses.

Bureaucrats and Congressmen have proved useful allies in the left’s war on conservative speech, but sometimes you need the old-fashioned kind of intimidation that only guns can provide.

Accordingly, radical leftists have enlisted the unintentional assistance of the local police in harassing conservative bloggers like Erick Erickson, Patterico, and Mike Stack of Anthony Weiner fame. Using a technique called "SWAT-ting," a 911 call is made, ostensibly from the blogger’s home, to tell the police he just killed somebody. A SWAT team descends on the house and orders the blogger to come out with his hands up.

Of course, enlisting the government’s help in the suppression of speech is not the only problem with SWAT-ting. It’s also a criminal act, something the left is increasingly resorting to to silence conservative voices.

The criminal behavior of those opposed to a California ballot initiative banning gay marriage provides a cautionary tale, as described by Justice Clarence Thomas:

One wonders whether such tactics are what Media Matters founder David Brock had in mind when he told Politico that his organization is mounting "guerrilla warfare and sabotage" against Fox News and its employees. But even without violence or property damage, harassment and intimidation can be a crime under state law and – if used to suppress free speech – under federal civil rights laws as well.

Media Matters and other groups on the left have the right to boycott, lawfully protest, and denounce opponents to their heart’s content. What they don’t have is the right to commit criminal acts or enlist the government’s help in silencing conservatives – no matter how morally superior and self-righteous the left may feel.

Curt Levey is a constitutional law attorney and the Executive Director of the Committee for Justice in Washington, DC. He can be reached at @Curt_Levey on Twitter.