If you put aside the emergency measures required by the financial crisis, three major policy ideas have dominated American politics in recent years: a plan that uses an individual mandate and tax subsidies to achieve near-universal health care; a cap-and-trade plan that attempts to raise the prices of environmental pollutants to better account for their costs; and bringing tax rates up from their Bush-era lows as part of a bid to reduce the deficit. In each case, the position that Obama and the Democrats have staked out is the very position that moderate Republicans have staked out before…

The normal reason a party abandons its policy ideas is that those ideas fail in practice. But that’s not the case here. These initiatives were wildly successful. Gov. Mitt Romney passed an individual mandate in Massachusetts and drove its number of uninsured below 5 percent. The Clean Air Act of 1990 solved the sulfur-dioxide problem. The 1990 budget deal helped cut the deficit and set the stage for a remarkable run of growth.

Rather, it appears that as Democrats moved to the right to pick up Republican votes, Republicans moved to the right to oppose Democratic proposals.