What politicians call "hot buttons" are, at their heart, issues of fundamental philosophy; they go to the core of how we view ourselves and our fellow beings and, therefore, have the power to move us.

Abortion and capital punishment were the premiere hot-button issues of the late 20th century, literally matters of life and death, and the interplay between them was tinged with irony. Those on the political right who saw abortion as legally sanctioned infanticide also tended to see capital punishment as justice, while those on the left who considered the death penalty to be legally sanctioned homicide also saw abortion as nothing more than a private medical procedure.

Translated into political terms, abortion and capital punishment have been "wedge issues" that could, if exploited adroitly, cleave significant blocs of voters - especially those in the middle of the political road - away from targeted candidates.

The interaction between abortion and capital punishment was a major factor in the California Democratic Party's resurgence during the 1990s. It abandoned its public opposition to putting murderers to death, surrendering to the state's overwhelming pro-capital punishment sentiment, while Republicans maintained their anti-abortion positions that alienated all-important swing voters.

It's been evident that national security - another of those life-and-death questions - would be the hot-button issue in the contest for the White House this year and perhaps in some congressional and senatorial duels. It's becoming clear, too, that illegal immigration has returned to the California political arena, driven by the enactment, and then hasty repeal, of a law granting driver's licenses to illegal immigrants. Gray Davis' signature on the bill was a major factor in his recall last fall - one often cited by challenger Arnold Schwarzenegger.

Suddenly, a new hot-button issue has arisen - elevated by events in California, but reverberating nationally: whether same-sex couples should be allowed to marry.

A Massachusetts Supreme Court decree that barring same-sex marriage is discriminatory lit the fire, but San Francisco Mayor Gavin Newsom's order to issue marriage licenses to gay couples, and the hundreds of subsequent weddings, brought the issue to a hard boil. Newsom says he was moved to act after hearing President Bush mention the "sanctity of marriage" in his State of the Union address, but San Francisco cynics also see it bolstering Newsom's shaky standing with a large and politically active gay community.

Whatever the motivations, Newsom's action has expanded into a classic hot-button issue with the potential for driving deep political wedges. While San Francisco and other urban enclaves may be supportive of full marriage rights for same-sex couples, California as a whole, as gauged by recent polls, is somewhat ambivalent. California voters passed a measure that seemingly barred recognition of same-sex unions four years ago, but since then a liberal Legislature has expanded rights of "domestic partnerships" to near-marriage status. Voter sentiment is now almost evenly divided on gay marriage itself.

Outside of culturally liberal California, however, it's a different story, with only about a quarter of U.S. voters accepting same-sex marriages. Whether out of moral conviction or political expediency, Bush is grabbing gay marriage as a diversion from the public's concerns about Iraq and the economy. He's putting intense heat on Democrats, especially Massachusetts Sen. John Kerry, his almost certain Democratic challenger.

Democratic politicians are scrambling - not wanting to alienate the gay community on one hand, but mindful of the larger public sentiment on the other. A case in point: Barbara Boxer, a very liberal U.S. senator from California running for re-election this year, quickly put some distance between herself and Newsom, aware that endorsing gay marriage could move all-important swing voters.

State Attorney General Bill Lockyer, who wants to run for governor in 2006, is another Democrat put on a limb by Newsom's surprising move, with Schwarzenegger shoving him even further out by pressuring him to oppose Newsom's actions. Lockyer is, with obvious reluctance, doing so.