Things have gotten tense with Afghan President Hamid Karzai, and two congressional anti-war advocates are planning to introduce a bill that would call for a withdrawal timetable.

Wisconsin Sen. Russ Feingold and Massachusetts Rep. Jim McGovern, both Democrats, plan to introduce a bill that would not establish a specific date for U.S. troops to exit, but rather call for Obama to create such a timetable. Feingold could introduce the bill in the Senate as early as next week, according to his office. The bill will call for a "flexible timetable" for Afghanistan withdrawal, Feingold's office said.

Obama announced in December that U.S. troops will begin withdrawing by July 2011, and there has been speculation that the process could begin even before that. Defense Secretary Robert Gates has said that the withdrawal will be conditions based--so it would appear there already is a flexible timetable. But even then, Feingold said he was disappointed that there was no timetable for the pace of U.S. withdrawal.

The Feingold/McGovern bill will be geared toward what happens after July 2011. Other than that date, Obama has given no specifics on how quickly things will proceed; the lawmakers want the president to flesh that out.

It's unlikely that Congress will actually force the administration's hand, when it comes to Afghanistan, but this bill will offer an entry point for discussion; the anti-war left will be able to rally around it.

And the timing is rich: it comes just after Karzai reportedly threatened to join the Taliban, and reports that his behavior has been "erratic." Peter Galbraith suggested he's on drugs.

With Karzai pretty much off the U.S.-alliance reservation, at least for the time being, the domestic politics of Afghanistan are at a intriguing moment. While Iraq was at the height of its prominence in domestic U.S. politics, Afghanistan was held up as a contrast--as the right war to be fighting--by Democrats and, perhaps most prominently, by John Kerry and President Obama in the '04 and '08 campaigns. Since Iraq faded, more questions over Afghanistan were raised. Can we win the war? If Karzai's government is rampantly corrupt, is it worth it? Was the election stolen outright?

The recent wave of trouble with Karzai isn't going to encourage U.S. support for the war. This effort to define the U.S.'s commitment in Afghanistan couldn't come at a more interesting, or uncertain, time.