U.S. Sen. Arlen Specter's decision to join the Democratic Party is a severe blow to Republicans in the Senate but does not create the single-party rule that has long crippled the Hawaii Legislature. Nevertheless, the potential of a filibuster-proof 60 Democratic votes in the Senate should lead Republican leaders to reconsider restricting their party's membership to a rigid and shrinking ideological base.

Sen. John Cornyn of Texas, head of the GOP's campaign arm, is right in branding Specter's move as a naked act of “;political self-preservation,”; but it was caused by conservatives' efforts to streamline membership requirements. Former Rep. Patrick J. Toomey, former head of a group of fiscal conservatives who have financed primary challenges by conservatives of incumbent Republican moderates, was favored to defeat Specter in next year's Pennsylvania Republican primary.

Specter's departure from the Republican Party leaves only two moderates among its Senate ranks: Olympia J. Snowe and Susan Collins, both of Maine. Snowe criticized her party's leaders for failing to grasp that “;political diversity makes a party stronger, and ultimately we are heading to having the smallest political tent in history.”;

That distinction has belonged for decades to Republicans in the Hawaii Legislature. Moderates and even conservatives have recognized that the only way to make a difference in either chamber is by joining the Democratic Party and eventually chairing a committee.

The most recent to make the switch was self-described “;social conservative”; Sen. Mike Gabbard in 2007. A Republican now dressed in Democratic armor, Gabbard candidly declared his choice to be “;a part of the majority party ... to be more effective.”;

As a result, the Legislature has become timid on social issues such as same-sex partnerships and physician-assisted suicide and robust on bread-and-butter issues following the agenda set for it by the state public-employee unions. There are no Gabbard Democrats in the U.S. Senate.

The description by Michael Steele, chairman of the Republican National committee, of Specter as “;left-wing”; is absurd. While Specter has supported abortion rights and expanded stem cell research and opposed a constitutional amendment to ban same-sex marriage, he supported the war in Iraq, favored school vouchers, backed President George W. Bush's Supreme Court nominees and has opposed Democrats on many issues.

Specter calls himself an independent and plans to continue in that vein, for example, breaking ranks with most fellow Democrats by opposing authorization to allow elimination of secret elections in union organizing.

Neither Snowe nor Collins is expected to leave the Republican Party, despite their increased discomfort. The difference between their situation and that of Specter is that they face no serious competition at the primary ballot. The GOP “;cannot prevail as a party without conservatives,”; Snowe observes. “;But it is equally certain we cannot prevail in the future without moderates.”;