There's a tendency among liberal Democrats to believe that the Republican Party is tougher and meaner and more effective. I think it's true that the GOP is more ideologically cohesive and less bound by social norms (the filibuster should be rare, impeachment is a response to extremely serious crimes, etc.) that might constrain their power.
On the other hand, ideological intransigence very frequently backfires on Republicans. Matthew Yglesias lists ways that the GOP could have prevented the Affordable Care Act but, out of sheer radicalism, failed:
[B]efore the right goes all-in on an ad hoc constitutional change driven by dislike of the Affordable Care Act, that different conservative behavior could have avoided this outcome. For example, Tom Davis would have been a formidable contender for a Senate seat in 2008, but the right decided he wasn’t conservative enough so they’d let Mark Warner win in a landslide. Then they decided Arlen Specter wasn’t conservative enough, so they drove him from the party and gave Democrats 60 votes in the United States Senate. Then they steadfastly refused to offer any compromise proposals that might have peeled the Ben Nelsons and Mark Pryors and Evan Bayhs of the world away from the pro-ACA coalition. I recall that after Scott Brown’s election there was mass panic in Democratic circles and lots of people wanted to abandon the ACA. For a while, I thought that those of us urging continued action might lose the argument to those who favored passing a “scaled-down” health care bill. But in the end we got a bailout from the GOP, which refused to offer any indication that it would actually accept such a bill.
One common thread here is the GOP's tendency to push for all-or-nothing outcomes -- rather than settle for a moderate Senator or bill, they make the choice between a pure conservative one and total defeat. If the Republican Party had more tactical flexibility in its candidate selection and legislative strategy, nothing like health care reform would have succeeded. Luckily, as Yglesias notes, the structure of the conservative movement is such that it is only able to criticize left deviation and never right deviation, even when right deviation created a worse outcome by conservatives' own terms. The primary challenge against Specter, in particular, was an utter disaster, yet you simply never hear Republicans admit this,