The Republicans are not policy oriented, they focus more on ideology and public relations. This gives them three advantages when it comes to not only obstruction, but passing their own legislation, like they did when they were in charge.1. Since policy isn't a big suit for them, they don't have huge battles on it within their party, they all basically go along with the same ideology, so it's easier for them to get on the same page and obstruct. Sometimes a few make small compromises but most of them fall in line. It's why somebody like John McCain can be considered a "moderate" even though he voted with Bush 90 percent of the time, it's so rare for any of them to dissent that it just seems like the ones that do are moderate. Also, Republicans set up a whole movement that will eat their own if somebody strays too much. You compromise even a little bit with Dems and, at least in the past, you risk a well-funded primary challenge.
2. Because of their public relations skills they have framed the debate and scared the hell out of Dems for decades now. Watch in the media, even now after the Bush years the status quo media doesn't challenge the idea of tax cuts, it's just assumed that they are great. Like you remember Charlie Gibson going after Obama and Hillary in the ABC debate last year? Oh if only the media went after Bush on Iraq or his policies that hard, and Chuck was talking about a tax that only affects the Richie Rich crowd, like himself. Look at the stimulus debate, the media had way more Republicans on polluting the airwaves with their polluted view. They controlled the whole debate, and the media was so in love with the idea that Obama had lost control of the whole situation. Well Obama isn't scared of these guys like the doormats in Congress who have been there for most of the last 28 years. He just got his bill passed and that was that. But congressional Dems are so scared of their shadows and the GOP debate framing that they'll give up the farm rather than put up much of a fight. I can tell you this, if Mitch McConnell had the majority Harry Reid has, he'd force Dems to filibuster and then pick off any Blue Dogs that he could to get it through. Reid isn't really willing to force these guys to filibuster. I can tell you this if they rammed through a better, bigger stimulus bill and named it something to frame the debate like "The American Freedom We Love Eagles And Apple Pie Job Creation Act" they almost assuredly would have still gotten Specter and Snowe to vote for it. Dems don't think like that, they are more fearful of 41 Republicans than the Republicans were of the majority party in the last few years. They're so beaten down from losing the debate they just automatically roll over now.
3. Since the GOP is so ideologically rigid, it helps them pass or obstruct legislation. By that same contrast, Dems are not as ideologically rigid. They have a coalition of Blue Dogs and others who lean in that direction on certain issues who almost always capitulate somewhat to the Republican side of things. Republicans can obstruct or pass legislation because while they have few people who will compromise to the left, they know they can pick off Dems to compromise to the right. And always remember every compromise is to the right. Like on the stimulus bill, the three Republicans didn't step over and vote for a bill that had no right-wing compromises in it. It was significantly watered down and that didn't even budge most Republicans. Republicans make no left of center compromises, but the Dems have people who consistently go the other way. They have a whole philosophy built around it, it's called the "Third Way." Could you imagine a moderate Republican getting a nomination? There hasn't been one since Gerald Ford. Bob Dole even became a supply-sider when he ran for president as did Bush Sr. Republicans simply know they can obstruct and get Dems to capitulate to them, but it really doesn't work the other way around.
Now technically, none of this has to happen. Dems could stop it, there are no real rules or anything in Congress that prevents it, but it's because of these reasons they do it anyway. It makes little sense, I know.
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=103&topic_id=428591&mesg_id=428688