As I wrote earlier today, social conservatives are kidding themselves if they think they will prevail on opposition to gay marriage. Add to the ranks of pro-same-sex marriage a new batch of lawmakers: Sens. Mark Kirk (R-Ill.) and Tom Carper (D-Del.). Sen. Lisa Murkowski (R-Alaska) said she was “evolving” on the issue, and yesterday Sen. Bob Casey (D-Pa.) announced he supports gay marriage.

Sen. Rob Portman (Alex Brandon/Associated Press)

There are a few take-aways from this.

First, Republicans who have not postured as defenders of “traditional” marriage don’t think they will be harmed by their shift, and evidence so far suggests they won’t. The Columbus Dispatch’s Joe Hallett writes on Sen. Rob Portman’s decision to support gay marriage:

Sen. Rob Portman was the keynote speaker for the Butler County Lincoln Day dinner on March 23 in Fairfield, and he received two standing ovations from the 400 or so partisan faithful on hand.

That is significant for this reason: Butler County Republicans are among the most socially conservative in Ohio. Generally speaking, they are not fans of gay marriage.

In his speech, Portman did not mention his stunning change of position nine days earlier on gay marriage. He never mentioned his son Will, 21, whose private revelation to his parents two years earlier that he is gay had spun in motion Portman’s conversion in support of gay marriage.

Instead, Portman talked about what he has discussed for the last 15 years at countless Lincoln Day dinners — fiscal and budgetary issues. The former federal budget director has built a career on his expertise as a fiscal conservative, and he gave the Butler County Republicans enough red meat to rouse them to their feet.

Hallett, who knows Ohio politics as well as anyone, surmises, “Conservative Republicans ultimately will stick by Portman, because their support for him always has been predicated on his economic stands, not social issues. Had he been an anti-gay-marriage demagogue, he might be paying a steeper price, but Portman assiduously has downplayed social issues during his career.”

Second, the rush to switch positions suggests the demand for the Supreme Court to supplant the elected branches of government by constitutionalizing marriage is premature and unnecessary. At this rate, there will be no Democrats who oppose gay marriage and fewer Republicans than anyone thought possible only a year or so ago.

Third, the nightmare for the GOP would be this: The Supreme Court affirms the constitutionality of DOMA. Democrats, supported by a few Republicans (including those like Kentucky Sen. Rand Paul who think marriage is an issue for the states), bring to a vote a repeal of DOMA, and then the remainder of the GOP Senate stages a filibuster. Talk about being on the wrong side of the optics. (It is not even clear Republicans could win a filibuster with Murkowski, Kirk, Paul and a few moderates or advocates of state-determined marriage rules defecting.)

Finally, yes, pols are sheeplike. It often takes only one or two brave souls (e.g. Portman) on an issue (e.g. Sen. Marco Rubio on immigration) to challenge the status quo. Then the rest come running to get on board and, if they can, affect the contours of the new policy. The screechy defenders of the status quo on the right should be nervous — their grip on the definition of “conservative” and their ability to scare elected officials are waning.