When the House passed a 10-month extension of key provisions of the Patriot Act last night, it was assumed that the Senate would follow suit quickly. And they will vote on the measure tonight. However, they will narrow the extension to three months, in a move with bipartisan support.

Sen. Joseph Lieberman (I-Conn.), chair of the Senate’s Homeland Security and Governmental Affairs Committee, said on Tuesday that Senate Democrats were likely to agree to an extension of controversial provisions in the Patriot Act, but only for a matter of months.

The Connecticut Independent, relaying talks that had occurred moments earlier in a caucus meeting among Democrats, said that discussion had centered around keeping the law in place “until May.”

Lieberman supports extending these provisions of the Patriot Act basically until the end of time, but he agreed to the 3-month extension. And so did the Senate Republican leadership, apparently. There will be a vote on this tonight.

Lieberman also referred to “ongoing investigations” that require the powers – roving wiretaps, national security letters, and the “lone wolf” provision that allows for investigating someone without known links to terrorist groups – in the short term. But instead of making that the basis for a long-term extension, it led to this three-month extension, with an opportunity to fully debate the issue before May.

Who pulled the plug on what looked like an inexorable march to a long-term extension? I know that Rand Paul sent a Dear Colleague letter last night urging his fellow Senators to vote against re-authorization, but I doubt he has the juice to convince 40 members. He would be able to hold it up for a while, which probably necessitated this change. In addition, Patrick Leahy, chair of the Senate Judiciary Committee, which has jurisdiction over the law, wanted some minor reforms to it put in place, so he could potentially be a roadblock here as well.

Ultimately, this probably only means that the Senate will spend a week of debate three months from now and then extend the whole thing past the Presidential election. But it’s so rare that civil libertarians see even a minor speed bump in the rush to deprive liberty, and even with the three-month extension, that’s what this represents.

If we just changed the name of the Patriot Act to the “emergency law,” do you think we could get the President to call for lifting it, like he did with Egypt’s?

UPDATE: The Senate passed this tonight, 86-12.