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As President Bush prepared to address Congress, some members of the House began calling for his impeachment — a call that has been growing over the last few months, when only the far fringes of the American left called for his ouster.

On Tuesday, eight-term California Democratic Rep. Maxine Waters said the president should be impeached for authorizing the warrantless surveillance of some Americans through the National Security Agency.

"If a president's untruthfulness about sexual relationships is an impeachable offense, then surely spying on American citizens, undermining the Constitution and contravening current standing law are impeachable offenses," Waters said comparing Bush's alleged crimes to ones former President Clinton was tried for.

• Click into the video tab to the right to watch a report by FOX News' Major Garrett.

At a recent forum on the president's electronic eavesdropping program, constitutional scholar Jonathan Turley called the NSA program an impeachable offense.

"This type of violation should be a textbook example of an impeachment issue because not only is it a federal crime, but it violates the doctrine of separation of powers," said Turley, a law professor at George Washington University.

But not all Democrats are on board yet. Senate Minority Leader Harry Reid, D-Nev., told FOX News that he doesn't think the threshold for impeachment has been crossed yet.

"As far as I'm concerned at this stage it's too early to talk about impeachment. We'll have to see if there's more to this," Reid said.

Attorney General Alberto Gonzales will defend the surveillance program before the Senate in a hearing scheduled next week. The president has said warrantless wiretaps and other surveillance were limited and necessary to thwart potential terrorist attacks.

The Nation magazine — one of the most influential liberal journals — said the wiretap issue has crystallized the case for the president's impeachment. On the Internet, a smorgasbord of impeachment tracts can be read.

But Reid said impeachment talk makes him uncomfortable.

"I'm not a big fan of impeachment. I think it should come only when all other avenues have been exhausted and that certainly hasn't been the case here," he said.

Republicans now control Congress, which means impeachment won't happen. But if Democrats win back the House in November, which is still seen as unlikely, Reid said he's not ready to jump on any bandwagons.

"I think we're way above the radar screen. I think impeachment this time is not something we need to talk about. I think we need to talk about the other failures of government and I don't think we need to go rushing off to the 'I' word," he said.

For some on the left, impeachment is a litmus test for Democratic lawmakers. So far, their numbers are still very small. But in a party that must rely on unity in a series of tight House and Senate elections, defections on the hard left could prove troublesome.

Click into the video tab above to watch a report by FOX News' Major Garrett.