A “bipartisan bill” isn’t a bill that includes ideas from both parties. It’s a bill that includes votes from both parties.When the subject of health care reform comes up, I often hear liberals complain that Republicans are hypocrites because they were labeling as socialist a plan that was very similar to what Mitt Romney signed in Massachusetts and Bob Dole pushed for the country back in the 1990s. Yes, there's some truth to that, but we should note a few other points. For one, Romney was governor of a very liberal state back then, and what a Democratic Massachusetts legislature can pass and their Republican governor can sign is not the same thing as you'll get elsewhere. Also, Dole and other Republican leaders pushed an Obamacare-style reform when Bill Clinton was pushing his model of health reform knowing full well it wouldn't pass. They were trying to siphon off votes from Clinton's plan and make it look more extreme in comparison. (It worked.)
Another point to keep in mind is that parties are allowed to change their minds. What's the current Democratic stance on same sex marriage? That's not to so easy to answer, but it's definitely not the same stance it was just a decade ago.
Finally, back to Ezra's point: There's no objective determination of how partisan or bipartisan the content of legislation is. What seemed like a bipartisan idea in one year might be treated very differently the next year if it looks like it has a chance of becoming law and making one party look good at the expense of the other. Bipartisan is as bipartisan does.